In a food processor fitted with a metal blade, place the flour, butter, and salt in the hopper and pulse for about 45 seconds or until the butter has been incorporated and the mixture appears to have a mealy texture. Add the water and pulse until dough just pulls together.Turn into a bowl and knead until all flour has been incorporated into a ball, being careful not to over-work the dough. Cut in half and form each half of dough into a disk. Wrap in plastic wrap and place in refrigerator for a minimum of 8 hours.When ready to roll the dough, place one dough disk (you can reserve the remaining dough disk for another pizza or double the filling ingredients above to make two tarts) on a well-floured work surface. Roll into a 12−14-inch circle. Remember, it does not need to be a perfect circle—it IS after all a RUSTIC tart!Transfer the dough to a cast iron skillet. Beginning about four inches from the edge of the crust, begin alternating layers of the zucchini and tomato slices in a circular pattern until you reach the center. Feel free to take a little creative freedom here—we like to add fresh herbs and really good cheese, whatever strikes your fancy at the moment.Gently fold edges of dough over toward the middle, on the top of the filling. Drizzle with olive oil and sprinkle with sea salt and freshly ground pepper.Bake for 45 minutes−1 hour at 425 degrees, or until the crust is golden brown and the filling oozes good juices. Cool for about 15 minutes before cutting and serving. We also like to serve this at room temp on a hot summer day with an arugula salad.Those jokes we tell in the summer about the monster-size zucchini and leaving a bag of squash in an unsuspecting friend’s car are hilarious, but we have found more useful ways to utilize this abundant vegetable—and this happens to be one of our favorites!