Ensconced in each of these savory cornmeal tartlets is a bounty of vegetables. On the short list: sweet red bell peppers, assertive kale, and cherry tomatoes that provide bursts of fruitness and juice.
Make the crust: Pulse flour, cornmeal, sugar, and salt in a food processor. Add butter; process until mixture resembles coarse meal. With machine running, add ice water in a slow, steady stream; process just until dough holds together. Divide dough in half, wrap in plastic, and refrigerate 1 hour (or up to 3 days).
Preheat oven to 350 degrees. On a lightly floured surface, roll out dough to 1/8 inch thick. Cut out six 9-inch rounds, gathering scraps and rerolling dough. Fit into 4 1/2-inch springform tart pans, and cut dough flush with tops. Place on a baking sheet, and refrigerate 30 minutes.
Make the filling: Heat oil in a large skillet over medium heat. Add bell peppers, and cook until just tender, 4 to 5 minutes. Add zucchini, squash, eggplant, and onion; cook, stirring, 2 minutes. Add wine and salt; season with pepper. Cook, stirring, until liquid has evaporated. Add kale, and cook until wilted, 2 to 3 minutes. Remove from heat. Stir in tomatoes, basil, and red-pepper flakes.
Spoon 1 1/4 cups vegetable mixture into each tart shell. Bake until crust is golden brown, 40 to 50 minutes. Top each tart with 1 tablespoon ricotta, and serve.