In a medium-sized bowl, add soy sauce, rice black vinegar, brown sugar, cornstarch, red pepper flakes, and mix until combined, set aside.
Heat a large pan on medium heat with oil and fry the tofu until all sides are golden, then remove, transfer to a plate lined with paper towels, and set aside.
Add the remaining oil into the same pan and sauté sliced red onions and crushed garlic cloves for about 1 minute.
Add slices of mushrooms and continue cooking for 3 minutes on medium-high heat.
Stir in the snow peas and cook for 2 minutes. Then, add the fried tofu and the soy sauce mixture.
Cover and allow it to steam for 2 minutes on medium-low heat.
Add hoisin sauce and adjust the seasoning. Then, turn off the heat and add a touch of sesame oil.
Serve with steamed Jasmine Rice.