Gather all your ingredients. Slice your round steak thin against the grain for optimal tenderness and set it aside. Chop your onion and bell peppers into bite-sized pieces.

In a large mixing bowl, combine soy sauce, cornstarch, sugar, garlic powder, ground ginger, salt, and pepper. Whisk until well blended. Pour the marinade over your thinly sliced steak, ensuring each piece is well coated. Cover and refrigerate for at least 15 minutes.

Prepare the glaze. In another mixing bowl, whisk together soy sauce, cornstarch, and sugar until fully combined and smooth. Set the glaze aside.

Heat vegetable oil in a large skillet over medium-high heat. Once shimmering, add chopped onions and bell peppers. Sauté for 3-5 minutes until slightly browned and tender.

In the same skillet, add more oil if needed. Remove the marinated steak from the refrigerator and add it to the skillet. Cook for about 5-7 minutes until browned and just cooked through.

Return the sautéed vegetables to the skillet. Pour the glaze over steak and veggies, stirring gently to combine. Cook for another 1-2 minutes until the glaze thickens.

Plate your warm Pepper Steak mixture over white rice. Serve immediately for best flavor.