Cooking with Kefir and a Chocolate Mousse Tart

My latest fermentation project, following in the footsteps of sauerkraut and bread starter, has been to culture kefir. To maintain this culture, you simply transfer a tablespoon of kefir to a fresh cup of milk and let it sit on your kitchen counter for about 24 hours. The result is a tart, thickened milk that I've started deploying in all sorts of guises. 

Using regular pint Mason jars for the culturing lends itself to preparing smoothies with my favorite trick of screwing the blender blade directly onto the jar. If you like, you can make yourself a daily smoothie after passaging a tablespoon of kefir for the next batch.

I've been preparing smoothies with about a cup of kefir, a half banana, and a teaspoon each of honey and chia seeds, which make a perfect midmorning snack.

I also found that adding a spoonful of kefir resulted in an extremely exuberant bread starter crumpet batter (reminiscent of Katharine Hepburn's waffle batter from Woman of the Year) and deliciously spongey crumpets.

For ~1 cup of old bread starter (~250 grams), add 1 teaspoon sugar, 1/2 teaspoon salt, and 1 tablespoon kefir. Mix well and then add 1/2 teaspoon baking soda and pour into well-oiled crumpet rings on a hot, well-oiled skillet to cook.

A final, recent use for my kefir was to add a bit of tartness to a chocolate mousse tart. Truth be told, this tart, for my son's birthday, was entirely motivated by my desire to use up a rye flour pie crust I had prepared for Thanksgiving and then accidentally left behind in the freezer when we dashed to the coast. Rye and chocolate is a classic combination, and filling a pie crust with chocolate mousse seemed like an easy way to please a newly minted eight year old.

I started with this recipe, and then, inspired by the success of using creme fraiche in chocolate fondue, I whipped in some kefir with the heavy cream (I've also used my kefir to culture heavy cream into creme fraiche, which works very well, but in this instance, I didn't have time). The resulting tart was a big success with the beaming birthday boy. 

Chocolate Mousse Tart with a Rye Crust

pie crust (based on Heidi Swanson's recipe)

1/3 cup (38 g) rye flour (I used rye flour from Lonesome Whistle Farm)

3/4 cup (88 g) unbleached all purpose white flour

1/8 tsp salt

4 Tbsp butter (1 stick), cut into 1/2 inch cubes

~1/6 cup ice water

Combine the flour and salt in a food processor and mix. Pulse in the butter cubes until they are lima bean sized. Then add enough water for the dough to just come together when you press it between your fingers. Mold into a disc, wrap with plastic wrap, and refrigerate for at least 30 minutes. Roll out into a 12 inch disc, drape into a buttered tart pan, flute the edges and patch where you need to, and now chill again for at least 30 minutes. Preheat the oven to 450 degrees. Cover the crust with aluminum foil and use rice or beans as pie weights. Bake for 10 minutes, then allow to cook completely before you fill the crust.

chocolate mousse

12 ounces bittersweet chocolate

1/4 teaspoon salt

1 teaspoon vanilla

2 3/4 cup heavy cream

1/4 kefir (or creme fraiche)

1/4 cup sugar

1. Pulse the chocolate, vanilla and salt in a food processor until the chocolate is in small pieces. Bring 1 cup cream to a boil in a heavy small saucepan. With the processor running, gradually pour the hot cream through the feed tube and process until the chocolate is melted and smooth. Transfer to a large bowl and allow to cool to room temperature.

2. Beat remaining 1 3/4 cups of of cream, 1/4 cup kefir, and 1/4 cup sugar in large bowl to stiff peaks. Fold the whipped cream into the chocolate mixture. Pour the mousse into prepared crust. Chill until set, about 6 hours.