Cook noodles in boiling water 6 minutes; drain. Combine soy sauce, vinegar, sugar, oil, and crushed red pepper, stirring well with a whisk.

Heat a large nonstick skillet coated with cooking spray over medium-high heat. Add bell pepper strips; sauté 2 minutes. Add bok choy; sauté 1 minute. Add tofu and garlic; sauté 2 minutes. Add noodles and soy sauce mixture; cook 2 minutes or until thoroughly heated, tossing well to coat. Sprinkle with green onions and cilantro.