This Sunchoke Soup (or, if you like, Jerusalem Artichoke Soup) is an elegant opening course for a festive Winter Dinner with your friends. The overall dish with its three components requires a little planning and diligent execution in order to achieve the desired outcome. In other words: this is not a last-minute endeavor and does not qualify for semi-homemade. Preparing and cooking the soup is pretty straight-forward. The Pickled Radishes are prepared using a technique called Sous Vide. This is a fancy term for simmering food in a vacuum-sealed plastic bag at a pretty precise temperature. I think you will enjoy this little sous vide experiment as an excellent entry to this popular cooking technique. And finally: The Watercress Puree is also a pretty simple fare. All together this is quite a few components to juggle. To achieve success it is best to divide and conquer. Start with the pickled radishes, then prepare the soup, and finally create the puree. You can keep the components warm for a little while—say, up to an hour. At dinner time it is good fun to assemble the course and I can assure you that the results are very elegant and rewarding.
The acclaimed chef Thomas Keller created a version of this recipe in his beautiful book, Under pressure: Cooking Sous Vide. His cooking is very sophisticated and a great inspiration that pushes my own aspirations. The Sunchoke Soup is the simplest recipe in the book. A good place at which to start on your ‘sous vide adventure.’
When it comes to serving the soup, I pour the heated soup from a carafe into the soup plate at the dinner table. All three components together really form a trifetta of flavors that work beautifully together. The richness of the sunchoke soup, the slight sharpness of the watercress puree and the wonderfully light sweet-sourness of the pickled radish make this soup a special event, one that your guests will not forget.
Let’s get started with the Pickled Radishes:
- one bunch of beautiful, fresh radishes
- ½ cup of regular vinegar
- ½ cup of sugar
- ½ cup of water
- Start combining sugar, vinegar, and water in a pan. Bring to a simmer and dissolve the sugar. This mixture will form your pickling liquid.
- We will quick-pickle our radishes under vacuum in a hot water bath. This cooking method is called sous vide. It allows for a very careful cooking of the food in a controlled environment. I like the results very much.
- You cut the radishes to your liking. I cut the big ones in quarters, some in slices. If you would like to be fancy you use a mellon baller for perfect little drops of radish.
- In they go to a plastic bag, then add some pickling liquid. Avoid the urge to use too much liquid; just a modest amount is needed.
- Suck the air out of your plastic bag with a vacuum sealer and seal the bag. Cook the radishes in a 185-degree hot water bath for, let's say 40 minutes. I used my sous vide hot water bath, which holds its temperature very precisely. But I would venture to guess that these radishes are pretty hardy and so, if you keep an eye on the thermometer, you pretty much can do it also in a good old pot.
- Once they're done, pour the bag into a bowl and let cool.
I discovered Sunchokes only recently. Their flavor is quite subtle, but very unique. It is easy to find them at the supermarket, living the final moments of their life in an under-appreciated corner of the veggie isle. Try to find the ones that are looking fresh and plump, pieces of good size and not the shriveled up ones seeming to be on their last breath. Peeling these morsels is a little pain in the you-know-what, but with a vegetable peeler this will be done in no time.
- Half a stick of butter
- One medium yellow or Spanish onion, thinly sliced
- One pound of sunchokes, peeled and sliced
- 1 tablespoon of sugar
- 1 quart of chicken stock
- Half a cup of heavy cream (yes, we must!)
- In a heavy-bottom pot melt the butter and sauté the sliced onion without allowing any sign of browning. The sliced onions should be shiny and soft. I challenge you to avoid browning them! Medium heat is best.
- Add the sunchokes, chicken stock, and sugar. Bring to a simmer and cook for about 15 to 20 min. The sunchokes should be completely soft. The chicken stock will reduce a little bit.
- Add the cream and bring to a simmer.
- Puree the whole thing in your trusty VitaMix.
- Back into the cleaned pot. Season with salt.
- You can keep the soup refrigerated for a while, reheating at dinner time.
The Watercress Puree
In his original recipe, Keller pairs the soup with an Arugula Puree. I modified the puree by using watercress. Watercress has a nice bitter aroma that provides contrast to the richness of the sunchoke soup. You need:
- 2 shallots, minced
- 1 tablespoon grape seed oil
- 2 sprigs of thyme leaves, stems removed
- 2 bunches of watercress, cleaned, no stems
- 1 bunch of spinach, cleaned, no stems
- salt and pepper
- 3 ice cubes
- Half a cup of chicken stock
- Half a cup of heavy cream
- 1 tablespoon of butter and 1 tablespoon of flour, kneaded together to 2 tablespoons of Beurre Manié
- 1 egg yolk
- Blanch the greens in a big pot of salted and boiling water for about 30 to 40 seconds. Dump the leaves in an ice bath and then drain on a towel, removing as much water as you can. Wringing out that water keeps your puree from being too saucy.
- Put the hot watercress and spinach into the VitaMix with 3 ice cubes and puree. This will stop the cooking and preserve the beautiful green color of the mixture. Set aside.
- In a sauce pan gently sauté the shallots with a tablespoon of grape seed oil until soft. Again, no browning. It should take about 3 minutes.
- Add the thyme leaves and cook for another few minutes. Still no browning, please!
- Add the chicken stock; cook for another 3 minutes. The shallots are now very soft.
- Add the cream and season with salt. What you've created should look somewhat like a white sauce. Strain and put aside.
- To assemble, mix the white sauce with a tablespoon of Beurre Manié and bring to a simmer, cook for 10 mins to remove any flour taste. This should now look like a think white sauce.
- Take off the heat and whisk in the egg yolk. Now you have a slightly more yellow think sauce.
- --Take a breather, we're almost there.--
- Mix two parts green puree with one part yellowish white sauce and reheat carefully over a small flame. Season again with salt and maybe a touch of pepper. This completes our puree. You can compare the consistency of the puree with the one in the photo. In my early attempts I created more of a green soup. If this happens, don't despair: it will still taste really good.
The assembly of this dish is fun: I line up all my plates in a row. Place the radishes, and then a spoonful of puree into each plate. Then, once the plates are set at the dinner table, I pour the beautiful, velvelty soup carefully into each.