Combine cornstarch and 2 tablespoons of cold water in a covered container and shake to combine. Place in a cool location. Combine remaining sauce ingredients in a medium bowl and set aside.

Heat the peanut oil over medium heat. Add the broccoli and toss to coat. Cook for 4-5 minutes until slightly softened. Remove and set aside.

Season the ground beef with salt/white pepper if desired. Cook and crumble the ground beef and diced onions over medium-high heat until browned and cooked through. Drain grease. Add the sliced bell peppers and cook for 1 minute.

Add the sauce mixture to the beef and bring to a boil. Let it simmer/reduce for 2-3 minutes. Shake the cornstarch mixture, then slowly stir it into the sauce. Let it continue to bubble gently until the desired thickness is obtained.

Reduce heat to low. Add the broccoli back and stir to combine and heat through. Serve over rice.