Add the olive oil to a large skillet and heat over medium high heat
Add the yellow onion, carrots, broccoli, garlic, and mushrooms and cook for 20-25 minutes, until the vegetables have cooked down and softened but are not mushy
While the vegetables are cooking, make a batch of the homemade teriyaki sauce and pour it over the vegetables. Stir to combine
Serve the teriyaki vegetables over white rice, brown rice, or stir fry noodles.