Instructions:

Prepare the sauce: In a small bowl, whisk together soy sauce, rice vinegar, sesame oil, sugar, red pepper flakes, and cornstarch. Set aside.

Cook the broccoli: Blanch the broccoli in boiling water for 30 seconds, then drain and rinse with cold water.

Stir-fry: Heat the oil in a large skillet or wok over medium-high heat. Add the mushrooms and cook until they release their moisture and start to brown.

Add the garlic and cook for 30 seconds. Add the broccoli and stir-fry for 2-3 minutes.

Add the sauce: Pour the sauce over the vegetables and stir continuously until the sauce thickens.

Serve: Remove from heat and serve immediately.