Guest post today by a dear friend and adventurous baker.

By Tim Vollmer

I’ve been baking my way through the Tartine No. 3 cookbook, mostly experimenting at home with the natural fermentation breads, but also trying my hand at some of the sweeter things in the book. It was my friend Cristina’s birthday last week, so I decided to turn to the back of the book and take a look at some of the desserts that would be good to make for a birthday picnic at Lake Merritt. Originally, I’d wanted to do a buckwheat and rhubarb tart–having had an incredible version of this the week before at Camino. However, the farmer’s market yielded no rhubarb at this time of year (Camino either had gotten early access to fresh rhubarb or had used some preserves from the previous year). In any case, I decided to go with one of the recipes straight from the book: a buckwheat apple tart.

Buckwheat tastes good. Like earth. You start this recipe by cutting the butter into cubes and chilling it in the freezer for 15 minutes so it’s nice and cold. Then, measure the buckwheat flour and spread it onto your surface. Sprinkle the very cold butter onto it, dust the top with some of that buckwheat flour, and begin rolling the butter into the buckwheat flour.

Keep rolling the butter into the flour until you’ve got big long flakes of butter and the dough looks really shaggy. You might need to grab a bench scraper and toss the mass over on itself a few times.

Whisk together the sucanat (this is a type of cane sugar), salt, cornstarch. Then you can beat in the egg yolks one at a time. Finally, whisk in the creme fraiche. Pour this mixture over your shaggy flour/butter mess, and mix it with a bench scraper (or your hands) until the wet ingredients have been incorporated into the dry ingredients. Roll it into a rectangle, fold the rectangle in half, and roll again. Do this about 4 times until the dough becomes smooth and there’s no big streaks of butter visible. Chill it in the fridge for an hour.

Peel the apples and grate them coarsely on a box grater. Do not grate your fingers. No one wants blood or skin in their tart. Toast the walnuts in a pan on the stove or in the oven. Don’t burn your nuts. After they’re done toasting, chop them. Add the nuts to the grated apple, along with the flour, cornstarch, melted butter, white sugar, vanilla bean seeds, and raisins. Give it a good mix.

When the dough is done chillin’, pull it out of the fridge and cut it into 2 pieces. Roll each out on your work surface, adding flour so that it doesn’t stick too much to the board. Buckwheat dough is a bitch to work with. Either that, or I’m terrible at rolling dough. Probably the latter. But seriously, it tends to tear even when it’s still pretty thick. I ended up pretty much pressing the dough into the tart pan after repeated failed attempts to roll it out in any consistent manner. I did a bit better with the top, thank God. When you’ve got it rolled out add the apple mixture into the prepared tart pan. Put the other half of rolled dough onto the top and press it down onto the apple mixture so there’s no air in there. Then press it only the sides of the tart pan and remove any overhang.

Ok, we’re almost there! You remembered to preheat the oven to 400F, right? Of course you did. Beat that egg yolk with the cream and paint the top of the tart with the egg wash. Then sprinkle some sugar over the top. Bake the tart for about 30 minutes, turning it halfway through. I turned down the oven to 375F after the first 15 minutes, because it seemed like it was coloring quite quickly. After 30 minutes (or whenever it looks browned and cooked), pull the tart out and let it cool on a rack.

Now, eat it. Delicious.

Tart dough
298g cold unsalted butter
312g buckwheat flour
192g sucanat
2 tsp kosher salt
1 tsp cornstarch
4 egg yolks (room temperature)
20g creme fraiche

Apple filling
48g walnuts
454g Granny Smith apples, grated
1 tbsp lemon juice
1 tbsp buckwheat flour
1 tbsp cornstarch
48g unsalted butter, melted
50g granulated sugar
1 vanilla bean, halved and seeds reserved
43g golden raisins, soaked and drained

Egg wash
1 egg yolk
2 tbsp cream