Many varieties of summer's best heirloom tomatoes should be used for this rustic, French country-style tart. It can be served with various soft cheeses mixed with practically any herb that is abundant and in season.
Make the dough
Combine the flour, salt, baking powder, and butter pieces in the bowl of a food processor or in a medium bowl if blending by hand. Blend just until the butter is incorporated into the dry ingredients, making sure not to overmix (some butter the size of peas is fine). Mix in the crème fraîche, again making sure not to overmix. Turn the entire mix out onto a cutting board and gently push it together into a pile. Wrap tightly with plastic wrap and refrigerate for 2 hours.
Make the filling
Put the tomatoes in a colander and sprinkle generously with coarse salt. Lay the tomatoes on several sheets of paper towel to drain (dried tomatoes will make a crisp tart).
In the meantime, heat the oven to 425°F. Dust a work surface well with flour and roll the dough into a 12-inch round about 1/8-inch thick. Dust flour under the dough if it starts to stick.
Carefully slide a rimless baking sheet under the dough. Leaving a 3-inch boarder, scatter the cheese on top of the dough, then arrange the tomatoes evenly over the cheese. Fold the edges of the dough over the tomatoes, making pleats as you fold and leaving the center of the tart open.
Bake the galette until golden brown, 30 to 40 minutes. Let cool on a rack.
While the galette cools, lightly dress the microradishes and microgreens with a bit of olive oil, some vinegar, and coarse salt. Drizzle the top of the galette with a touch of olive oil and a sprinkle of coarse salt. Slice the galette and serve with a few dressed microradishes and greens, if desired.
Photo: Ellen Silverman