3 tablespoons fresh lime juice3 tablespoons brown sugar1 tablesp minced1/2 teaspoon grated fresh ginger1/4 teaspoon red pepper flakes (optional)2 tablespoons vegetable oil8 ounces extra-firm tofu, cutinto 3/4-inch cubes1/2 red bell pepper, julienned1 medium carrot, julienned3 large zucchini, julienned1 cup bean sprouts1