Make the crust by putting the flour, butter, and salt in a food processor. Pulse until the butter is pea sized. Turn the food processor on and stream in 2-3 tablespoons cold water, until mixture comes together. Stop the processor. Remove dough, cut in half. Form each piece into a disk, wrap in plastic wrap and put in the refrigerator while you make the filling.
Heat the olive oil in a large skillet. Add the leeks and cook for about 5 minutes. Add the garlic and zucchini, and cook for a few more minutes. Add the corn and tomatoes, and stir. Season with salt and pepper, and turn off the heat.
Line a large baking sheet with parchment paper. Remove one piece of the crust dough from the fridge and roll it out to 1/4 inch thick on a floured surface. Carefully transfer to baking sheet.
Add the filling to the center of the crust, using a slotted spoon so that you don’t have too much liquid. Pat the filling into the center, leaving a few inches on the edges. Carefully fold the edges over the filling, leaving the center open. Sprinkle the goat cheese on top. Brush the crust with some milk.
Bake the tart until the crust is browned and the vegetables are tender. The tomatoes should be kind of jammy and the cheese lightly browned. Check your tart at 20 minutes, and keep checking it every 5-10 minutes after that. Mine took about 45 minutes or so.
Remove from oven and allow to cool for a few minutes. Sprinkle with the kale sprouts, slice into wedges and serve.