In a large nonstick skillet, warm the oil over medium-high heat. Stir in the eggplant, bell peppers, zucchini, sweet potato, onion and garlic. Stir-fry until the vegetables begin to soften, about 10 minutes. Stir in 2 tablespoons each of the basil and mint. Reduce the heat to medium-low, cover, and cook until the vegetables are very tender, about 10 minutes. Remove the large pieces of red bell pepper from the skillet Add the ¾ cup tomato juice and 3 of the canned tomatoes to the processor and process to pur.Return the pur tomatoes, the vinegar, black pepper, sugar, and red pepper flakes, and bring to a boil over medium-high heat, breaking up the tomatoes with a spoon.Reduce the heat to low and simmer while you cook the pasta.Bring a large pot of water to a boil. Add the ziti and cook until al dente, 10 to 12 minutes, or according to package directions.Drain the pasta in a colander and transfer to individual dinner plates.Spoon the ratatouille sauce over the ziti. Sprinkle the remaining basil and mint on top and serve.