Drain tofu on paper towels. Cut crosswise into ¼ inch tick slices. Set aside.Cut onion into 8 wedges. Set aside.Heat the wok over medium high heat about 5 minutes or until hot. Add tofu and fry about 8 minutes per side or until golden brown, turning once. Remove tofu with slotted spatula to a baking sheet lined with paper towels; drain. Drain all but 2 tablespoons of oil from the wok.Add onion to the wok and stir fry 1 minute. Add zucchini, squash, and mushrooms; stir fry 6 to 7 minutes until zucchini and squash are crisp tender, stirring occasionally.Add red pepper, snow peas, and water to the wok. Stir fry 2 to 3 minutes or until crisp tender. Stir in soy sauce, tomato paste, salt, and black pepper until well mixed. Add tofu; stir fry until heated through and coated with sauce.Transfer to a serving dish.*Remaining tomato paste may be transferred to a small resealable plastic food storage bag and frozen.