Slice the red bell peppers, snap peas, and carrots. Set aside.
Heat two tablespoons of olive oil in a large skillet over medium-high heat. Sprinkle the cubed chicken with salt and peppers. Transfer the chicken to the pan and fry for 5-7 minutes, until fully cooked, turning occasionally to brown all sides. Remove from the pan and set aside.
Heat one tablespoon of olive oil in the skillet. Add the sliced vegetables. Stir-fry for about three minutes until tender-crisp.
Add the cooked chicken and teriyaki sauce. Stir to coat and cook until heated through.
Garnish with green onions and toasted sesame seeds.