Heat the oil in a pan over medium heat. While the oil is heating, dice onion and red pepper. Mince garlic.
Add onions and pepper to pan and saute 5-10 minutes, or until onion is soft and translucent. While the onions and pepper cook, cut broccoli into bite-sized pieces. Remove tofu from the package and slice into 3/4 inch - 1 inch blocks by cutting the whole block in half depth wise, then into squares width wise and length wise.
When the onions and peppers are ready, add the garlic. Stir for 10 seconds just to release the garlic aroma, then add the broccoli and tofu. Cook for 10-15 minutes.
While stir fry is cooking, add all sauce ingredients to a small saucepan on medium heat. Stir until sauce reaches desired consistency, about 5 minutes.
When the stir fry is ready, add in the teriyaki sauce and mix until hot. Serve immediately.