Place the oil in large skillet set over medium heat. Add the onion, bell pepper, eggplant, and zucchini and cook until tender, about 5 minutes. Add the wine, pasta sauce, water and sugar, bring to a simmer, and simmer 5 minutes. Remove from the heat and cool to room temperature. Bake the tart shells as per package directions; cool to room temperature. Remove tarts from their foil liners and set them on a baking sheet lined with parchment paper. Fill the tarts with the ratatouille mixture and sprinkle with the cheese. Bake in a 350 degrees F oven 10 minutes, or until the filling is well heated through. Arrange on a platter and serve.

Note: For instructions on preparing these tarts in advance, see the expanded version of this recipe at thriftyfoods.com, and scroll down to “options.”