Modernist Vichyssoise Recipe from Modernist Cuisine at Home

Modernist Vichyssoise

The following guest post is by Brenda (@mightyvanilla).

While the full five volume set of Modernist Cuisine is a culinary reference to be reckoned with, its smaller sibling, Modernist Cuisine at Home, is a more practical day-to-day book which stands alone yet still contains a good deal of information from its big brother. Modernist Cuisine at Home is divided into 2 parts and 23 chapters.

Part 1 is composed of four chapters on the equipment, tools and ingredients which are important to have in a modernist kitchen. They also describe different options for some of the equipment. For example, if you don’t want to splurge on a vacuum chamber sealer and immersion circulator then you can still make sous vide recipes with “do it yourself” home versions, but the results won’t be exactly the same.

Part 2 makes up the bulk of the book and contains hundreds of practical do-at-home recipes with detailed instructions and step-by-step photographs. At the beginning of each recipe, the authors provide a level of difficulty rating and a list of any specialty equipment that might be needed. Advanced recipes will indicate the reason behind the rating.

Soup is considered to be one of the easiest and most satisfying things to make at home. Despite its long name, vichyssoise is essentially a blended soup made of pureed leeks and potatoes, thinned out with stock and enriched with cream. Modernist at Home’s version is rated at an advanced difficulty level due to an unusual ingredient (diastatic malt powder) and requires some specialty equipment (sous vide setup, chamber vacuum sealer).

Detailed instructions for Modernist Vichyssoise, pages 1 & 2 of 3

This description of Modernist Vichyssoise intrigued me:

“The secret to velvety-smooth potatoes is diastatic malt powder, an ingredient available from specialty baking or brewing supply stores, that converts potato starches into sugars and leaves no trace of gumminess or graininess. Excessive cream or milk is no longer needed; in fact you can make this recipe with no cream at all. The main liquid is pure leek jus, squeezed from whole, cooked leeks.”

There’s a great video and accompanying recipe on the Modernist Cuisine website on how to make creamy pureed potatoes using diastatic malt powder – this is essentially the potato cooking technique outlined in the book’s vichyssoise recipe. A related Modernist Cuisine article describes the science in more detail. (I’ve heard that mashed potatoes can become thick and gluey if they are made in a food processor or blender but I believe this Modernist technique fixes that. I was able to puree the potatoes in a high powered VitaMix blender without any problems.)

The first step in making the Modernist Vichyssoise recipe is to peel the potatoes and cut them into pieces before simmering them in water with some salt and sugar. (The cookbook indicates that the sugar enhances the sweetness of the potatoes.) However, the Fat Duck Cookbook has a very interesting technique for simmering potatoes which I have used ever since I read about it.

Heston Blumenthal, the chef/owner of the Fat Duck restaurant and one of the pioneers of modernist cooking, found that potato peels contain a great deal of potato flavour. Simmering the peels in water makes the water taste like potatoes, and cooking potatoes in the flavoured water makes the potatoes taste even more intensely of themselves. I tried this out in a blind taste test to compare potatoes cooked in regular water versus potatoes cooked in potato-peel water. The Fat Duck cookbook recommends simmering the peels for 40 minutes but I found that a much shorter simmer (5-10 minutes) still made a noticable difference. When a dish only has a minimal number of ingredients, it’s always a good idea to use the highest quality that you can reasonably get and to get as much out of those ingredients as possible. Other than simmering the potatoes in potato-peel water, I followed the rest of Modernist’s Potato Puree recipe as stated.

After the potato pieces were simmered until very tender, they were drained and tossed with a small amount of diastatic malt powder and then blended in a VitaMix blender. The blended puree was very thick, had a starchy/pasty/sticky texture, and tasted intensely of potato. The blended puree was sealed into a plastic bag and cooked sous vide for 30 minutes to let the diastatic malt powder convert the potato starch into sugar. After the sous vide step, the potato puree became sweeter and the texture was less starchy/pasty and more like a normal potato puree. The puree is then heated to 75C to stop the enzymatic reaction of the diastatic malt powder.

When it came to the leek jus component, I didn’t have enough weight using just the white part of the leeks only. It seemed wasteful to not use the green parts too so I decided to use some to make up the needed weight.

The Modernist recipe called for measuring out 400g (1 ⅔ cups) of potato puree but I used the entire cooked amount rather than having a tiny bit left over. The original recipe also called for adding 1 Tbsp of salt to the vichyssoise but this seemed excessive so I started with 1 tsp and adjusted slightly higher to taste. Vichyssoise is traditionally served chilled but I prefer most soups to be warm, especially in the winter. Note that chilled soups may need additional seasoning because colder temperatures may numb flavours on the tongue.

The Modernist Vichyssoise recipe includes a garnish of blanched julienned leeks and potatoes mixed with chives but I wanted something with more texture to contrast against the silky smooth soup. I had a bit of uncooked light green leek parts leftover so I thought it would be ideal to turn them into a crispy garnish. I used the fried leeks recipe in the More Best Recipes cookbook which called for tossing julienned leek strips with a small amount of flour and shallow frying them for several minutes. This only took a short amount of time to complete (relative to the rest of the recipe!) and I thought it complemented the soup nicely. Crispy fried bacon bits or freshly made croutons would also make excellent garnishes as well.

The final soup was incredibly smooth and creamy with a silky velvety texture. It was sweet and had a very strong potato flavour. I could also taste the sweet leek juice, and the crispy leeks add a nice textural contrast. This deceptively simple looking soup is a great showcase for how Modernist techniques can enhance and refine a well known dish. It’s very simple to make ahead and would be an ideal dish to serve for a dinner party.

Modernist Vichyssoise

– adapted from Modernist Cuisine at Home

Yields 4 servings (950g total, ~4 cups)

Ingredients

Potato Puree

• 1 kg (1 L) water
• 500g (3 ⅔ cups) Yukon Gold potatoes, peeled and cut into 1” pieces
  • (optional: reserve the peels for flavouring the potato cooking water)
• 15g (5 tsp) salt
• 10g (2 tsp) sugar
• 5g diastatic malt powder

Leek Jus

• 1kg (4-5) leeks, white parts only (or green parts as well), washed and halved lengthwise

Vichyssoise

• 400g (1 ¾ cups) potato puree
• 400g (1 ⅔ cups) leek jus
• 100g (½ cup) heavy cream
• 4g (1 tsp) salt

Crispy Fried Leeks (optional)

• 1 medium leek, white and light green part only, halved lengthwise and sliced into very thin strips
• 1 Tbsp flour
• ½ cup olive oil or vegetable oil

Garnishes

• 9g (3 Tbsp) finely chopped chives
• Crispy Fried Leeks (optional, see above)

Notes for success

• Simmering the potato peels in the water before adding the potatoes will make the puree taste more intense.
• When sealing the potato puree in the chamber vacuum sealer, be sure to remove all of the plastic plate inserts first so that the level of the puree is higher than the sealing bar. If the puree ends up being higher than the sealing bar, puree will get pulled out of the bag which makes a mess in the chamber.
• All of the soup components can be made ahead of time and stored for several days.
• The potato puree can be blended and cooked sous vide ahead of time, and then heated to 75C just before adding the leek jus. It is easier to mix leek jus into the potato puree while the potatoes are still warm.

Method

Potato Puree

1. Preheat a water bath to 52C/126F.

2. Scrub the potatoes well and peel them.

3. (Optional: Reserve the peels for flavouring the potato water.)

4. Bring the water, salt and sugar to a boil in a large pot. (Adding 1-2g of sugar for every 100g of water helps preserve the natural sweetness of the potatoes.)

5. (Optional: Add the potato peels and simmer for 5-10 minutes, then remove them from the pot with a large slotted spoon and discard).

6. Add the potato pieces to the pot, reduce the heat and simmer until the potatoes become very tender, 30-40 minutes. (It may take longer if your tap water is rich in minerals.)

7. Drain the potatoes.

Simmered potatoes tossed with diastatic malt powder

8. Sitr the diastatic malt powder into the warm potatoes.

Blending the potato & diastatic malt powder

9. Place the warm potato mixture in a blender – the more powerful, the better (such as a VitaMix) – and puree until it becomes smooth and sticky. You may need to pause a few times to stir the potatoes and scrape down the sides of the blender.

Potato puree before being sous vide

10. Place the potato puree in a plastic bag. Remove all of the plastic plate inserts from the chamber vacuum sealer, then seal the bag in the chamber.

11. Cook the puree sous vide for 30 minutes.

Potato puree after being sous vide

12. Transfer the puree to a pot, and heat it to at least 75C/167F, stirring occasionally. (This halts the enzymatic reactions.) Use a thermometer, and note that the mixture may boil below this temperature.

13. Cool the puree and chill it in the refrigerator if making ahead.

Leek Jus

1. Increase the temperature of the water bath to 90C/194F.

Vacuum sealed leek parts before being sous vide

2. Vacuum seal the halved leeks.

3. Cook the leeks sous vide for 2 hours.

4. Allow the leeks to cook slightly, then strain the liquid from the bag(s).

5. Squeeze the leeks by pressing them with a spoon to collect as much jus as possible. You should have close to 400g (1 ⅔ cups) of jus. Discard the pulp (or reserve/freeze for making vegetable stock).

Vichyssoise

1. Measure 400g (1 ⅔ cups) of the leek jus and 400g (1 ¾ cups) of the potato puree into a medium saucepot.

2. Stir the jus, cream and salt into the potato puree.

3. Season with additional salt and pepper to taste.

4. If serving the vichyssoise cold, refrigerate the soup until fully chilled, at least 2 hours.

Crispy Fried Leeks (optional)

1. Place the leek strips in a strainer and rinse thoroughly to remove any dirt caught between the layers. Gently blot the leek strips dry using a tea towel.

2. Toss the leek strips with the flour and a pinch each of salt and pepper in a bowl.

3. Heat the oil in a 12 inch skillet until shimmering. Test the oil temperature using one leek strip; it should sizzle and make small bubbles in the oil.

4. Use your hand to scoop up half of the leek strips, leaving excess flour in the bowl, and gently add the leeks to the oil in an even layer.

5. Fry the leek strips, stirring often, until they are golden brown, 4-5 minutes. (They will darken as they cool.) Drain the fried leeks on paper towels and season with a light sprinkling of salt and pepper.

6. Fry the rest of the leeks in the same way.

7. Allow the fried leeks to cool and store them in an airtight container until ready to use.

To finish & serve:

1. If serving the vichyssoise hot, reheat the soup on the stovetop or in the microwave.

2. Distribute the vichyssoise evenly between serving bowls.

3. Garnish the soup with the crispy leeks and chives just before serving.