Tomato and Plum Galette with Black Pepper-Parmesan Crust

In a large mixing bowl, combine the flour, Parmesan, black pepper, and sea salt.
Grate in the butter, then mix it into flour with your fingertips. 

In a small bowl, combine sour cream and ice water. Drizzle over flour mixture,
using a Silicone spatula to fold in the liquid. Turn out onto a lightly floured
surface, gather into a disc, and wrap tightly with plastic. Chill in refrigerator for 30
minutes (or an hour or more if it’s a hot, humid day).

Preheat oven to 425° F.  Set out a rimmed baking sheet.

Core and cut tomatoes into 1/4-inch slices. Use your fingertips to scoop out all
the seeds you can, then line a plate with paper towels, scatter the tomato slices
over top, and sprinkle with sea salt. Cut plums into 1/4-inch slices.

On a lightly floured sheet of parchment, roll dough into a rough 14-inch circle.
Brush any excess dough or flour from the parchment, reserving leftover dough.
Scatter 2 tablespoons Parmesan in a 12-inch circle in the center of the dough
circle. Next, arrange a band of tomatoes around this 12-inch circle. Working
inwards, alternate circles of plums and tomatoes, tucking each layer against the
other so they stand up at a diagonal. Working quickly, fold up the sides of galette,
pressing along each seam. If needed, use any excess dough to patch holes.
Lightly brush edges with the egg and sprinkle with a generous pinch each sea
salt and pepper.

Carefully lift parchment, galette and all, onto a rimmed baking sheet. Trim
parchment as needed. Bake at 425° F for 10 minutes. Pull galette out of oven,
sprinkle with remaining Parmesan, rotate pan, and slide back into oven. Lower
heat to 375° F and bake until galette is a rich golden brown, 20 to 25 minutes
more.

Cool for 15 to 20 minutes, scatter tarragon leaves over the top, and then serve
warm