Place tofu, zucchini, red bell pepper, and mushrooms in a bowl. Mix sriracha sauce, soy sauce, sesame oil, onion, jalapeno, and pepper in a small bowl, and pour over tofu and vegetables. Toss lightly to coat. Cover, and allow to marinate at least 1 hour in the refrigerator.
Preheat an outdoor grill for medium-high heat, and lightly oil the grate.
Thread tofu and vegetables on to skewers. Grill each skewer 10 minutes, or to desired doneness. Use any remaining marinade as a dipping sauce.
