In a small bowl stir together water, soy sauce, sugar, and cornstarch. Set aside.
Wrap tortillas in foil and bake in a 350° F 175*C) oven (about 10 minutes or till warm.
Meanwhile, pour oil into a wok or large skillet. Preheat over medium-high heat (add more oil if necessary during cooking). Stir-fry gingerroot and garlic in hot oil for a few seconds. Add carrots; stir-fry for 1 minute. Add cabbage and zucchini; stir-fry for 1 minute. Add mushrooms, bean sprouts, and jicama; stir fry for 1 to 2 minutes more or until vegetables are crisp-tender. Push vegetables from center of wok or skillet.
Stir soy mixture; add to center of wok or skillet. Cook and stir until thickend and bubbly. Add tofu and sliced green onions. Gently stir all ingredients together to coat. Cover and cook (about 2 minutes more or until mixture is heated through.
Spread warm tortillas with hoisin sauce. Spoon the vegetable mixture onto each tortilla. Fold over one side of tortilla to cover some of the filling. Then fold the two adjacent sides of tortilla over filling. Secure with wooden picks, if necessary. Serve immediately.
Servings: 4 to 5