Combine water, soy sauce, bouillon, cornstarch, sugar, garlic, rice vinegar, sesame oil, ginger, and red pepper flakes in a saucepan over medium-high heat. Whisk until cornstarch is fully dissolved, about 3 minutes. Bring to a boil, stirring frequently. Boil until thickened and reduced by a third, about 10 minutes. Remove from heat.
Pour peanut oil into a large skillet or wok. Add cabbage, asparagus, carrots, broccoli, snow peas, and celery. Saute over medium-high heat until tender but not mushy, stirring with a spatula, about 10 minutes. Reduce heat to low; pour sauce over vegetables and stir until completely coated. Serve over rice.