Place cauliflower florets in a bowl. Add soy sauce, garlic powder, onion powder and avocado oil, and toss until combined. Add cornstarch and toss to coat.
Cook peppers and pineapple. Add the prepared sauce, reduce heat and simmer while stirring. Add cauliflower florets to the skillet, toss until coated. Garnish with chopped green onions and sesame seeds. Serve.