Tarragon Mousse

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Tarragon MousseTransforming a sauce with gelatin into a fluffy, distinctly flavored mousse is one of those little tricks that really elevates your presentation. It adds what one of my cooks, Mira, used to call a T.O.E., or “touch of elegance”—that extra something that makes a dish more special. Gelatin might seem intimidating to work with, but in fact it’s remarkably simple.
I use this mousse mainly as a garnish for cauliflower velouté. Plain crème fraîche was my usual garnish for this dish, but I didn’t like how it sank and melted into the soup. A puff of light-as-air mousse that floats on the surface of the soup makes the dish more refined.
The same gelatin technique can be applied to any of the flavored crème fraîche recipes on the preceding pages. You can also flavor this mousse with a different herb, like finely chopped chives or flat-leaf parsley.


  • 8 cups water, plus 1 tablespoon
  • 2 tablespoons plus ½ teaspoon salt
  • 4 cups ice cubes
  • ½ cup packed tarragon leaves
  • 1 cup crème fraîche or sour cream
  • ¾ teaspoon powdered gelatin
  • 0.125 teaspoon Tabasco sauce
  • ½ teaspoon lemon zest
  • ¼ teaspoon tarragon vinegar or white wine vinegar
  • ½ teaspoon Dijon mustard
  • 0.0625 teaspoon sugar (optional)
  • 2 tablespoons heavy cream
How to Make It
  1. In a 2-quart saucepan, bring 4 cups of the water and 1 tablespoon of the salt to a boil. Set up a metal bowl with the remaining 4 cups of water, the ice cubes, and 1 tablespoon of the remaining salt. Have a fine-mesh strainer ready to go as soon as the salted water is boiling. Blanch the tarragon leaves, cooking for about 5 seconds. Scoop out the leaves with the strainer and plunge them directly into the ice water to fully cool them. Remove the leaves from the ice water, roll them up in a kitchen towel, and squeeze out the excess liquid. Finely chop the blanched tarragon.
  2. Place ½ cup of the crème fraîche in a food processor. Add the tarragon and purée for about 30 seconds, or until the tarragon is evenly dispersed. Add the remaining ½ cup crème fraîche and purée for 30 seconds to 1 minute, until the sauce is evenly blended and the tarragon is very fine.
  3. In a small bowl, sprinkle the gelatin over the remaining 1 tablespoon water and let bloom for 5 to 10 minutes. Meanwhile, transfer the crème fraîche mixture to a metal mixing bowl. Add the Tabasco, lemon zest, vinegar, mustard, and the remaining ½ teaspoon salt and mix well. Taste and add sugar if needed.
  4. Place your smallest saucepan (1 to 2 quarts) over medium-low heat and add the heavy cream. As soon as it is hot (don’t let it burn!), remove the pan from the heat and drop the bloomed gelatin into the hot cream. Using a rubber spatula, stir quickly until no lumps of gelatin remain.
  5. Using the spatula, scrape the cream mixture into the bowl holding the tarragon crème fraîche, being careful to get it all. Whisk until thoroughly combined. Pour the crème fraîche mixture into a container large enough so that there is about ¾ inch of headspace. Cover and refrigerate until fully set, about 3 hours, or for up to 4 days.
  6. Just before using, whisk the mousse briefly to fluff it up. To serve, shape a quenelle of the mousse and place atop the dish you are garnishing.

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