In a small bowl, mix all sauce ingredients until blended. Slice an edge from each pita bread, and carefully open pockets. In a medium bowl, combine tofu, tomatoes and spinach. Add 1/4 cup of sauce, and toss gently to mix. Spoon the mixture into each pocket. Divide sprouts and avocado among the sandwiches. Drizzle each with 1 tablespoon of tahini sauce. Serve right away.