Prepare the Ingredients : Chop all vegetables (dice onion, chop bell pepper, julienne carrots, and cut broccoli into small florets) and set aside for easy assembly. In a small bowl, whisk together all sauce ingredients: brown sugar, soy sauce, rice vinegar, sesame oil, ginger, and crushed red pepper flakes. Set aside.

Cook the Ground Beef : Heat olive oil in a large skillet or wok over medium-high heat. Add the ground beef and cook, breaking it apart with a wooden spoon, until browned and fully cooked (about 5–7 minutes). Drain any excess fat if necessary. Add diced onion and minced garlic to the beef. Cook for an additional 2–3 minutes until the onion is translucent and the garlic is fragrant.

Add the Vegetables : Toss in the chopped red bell pepper, julienned carrots, and broccoli florets. Stir-fry for 5–7 minutes until the vegetables are tender but still crisp. (If you prefer softer vegetables, add a splash of water and cover the pan briefly to steam.)

Add the Sauce : Pour the prepared sauce over the beef and vegetable mixture. Stir well to coat all the ingredients evenly. Cook for another 2–3 minutes, allowing the sauce to thicken slightly and meld with the dish.

Garnish and Serve : Remove the skillet from heat. Garnish the stir fry with sliced green onions and toasted sesame seeds. Serve immediately over steamed white or brown rice, noodles, or in lettuce wraps for a low-carb option.