Heat oil in a large skillet. Add bell pepper, onion, broccoli, and zucchini. Season with salt and pepper. Cook 5 minutes. Remove and set aside.
Add ground beef to the same pan. Brown, then stir in garlic. Drain grease.
In a bowl, mix sauce ingredients.
Return veggies to the pan with beef. Add sauce and stir to coat. Simmer 2–3 minutes.
Serve over rice or noodles. Garnish with green onions and sesame seeds.
