In a bowl or jar, whisk together cornstarch and cold water until smooth. Add soy sauce, juice, maple syrup, vinegar, sesame oil, ginger, and garlic. Stir well or shake the jar until everything blends. This quick sauce is the secret to a glossy finish.
Heat one tablespoon of avocado oil in your skillet or wok. Once hot, add tofu cubes and cook for around 10 minutes, flipping often. They should turn golden and slightly crispy on all sides. Remove the tofu from the pan and set aside.
In the same skillet, pour in the second tablespoon of oil. Add sliced red onion and cook for about 2 minutes until softened. Then toss in the carrots and let them cook for 4-5 minutes. This gives the dish its first layers of sweetness and crunch.
Next, stir in the red and yellow bell peppers, broccoli florets, and snow peas. Let them cook for another 5-7 minutes, stirring frequently. You want them tender yet crisp and brightly colored for the best flavor.
Lower the heat to medium. Add tofu back into the skillet, then pour in the teriyaki sauce. Stir gently until everything is coated, and cook for another 1-2 minutes until the sauce thickens slightly. Your kitchen will smell amazing at this point!
Finish by sprinkling sesame seeds and fresh green onions on top. Serve right away over warm rice, and enjoy the flavors blending together.