Heat 1 Tbsp. olive oil in large nonstick skillet over high heat. Meanwhile, quickly cut steak into thin slices. Add steak to skillet and sprinkle with Knorr® Beef flavor Bouillon. Cook for 4 to 5 minutes, stirring occasionally. Remove from skillet; set aside. While beef is cooking, thinly slice pepper and onion and chop garlic. Add the remaining 1 Tbsp. olive oil to same skillet and cook peppers and onions for 4 minutes. Stir in garlic and cook 30 seconds. Return steak to skillet, toss. Serve with cooked quinoa.