Place beef in a mixing bowl and add soy sauce and pepper; stir to combine and set aside. In a separate mixing bowl, whisk together all sauce ingredients; set aside.
Add half the olive oil to a large skillet over medium- high heat then add the beef. Cook until browned on all sides and cooked through. Pour contents of the skillet, including extra liquid, into a bowl; set aside.
Add remaining 1/2 Tablespoon of oil to the skillet and add bell pepper, peas and carrots. Sauté for 4- 5 minutes, or until vegetables are tender.
Pour the beef and extra juice back into the skillet and stir to combine. Pour sauce in the skillet and toss to coat. Let simmer for 3-4 minutes, or until thickened. Garnish with green onion and sesame seeds before serving.