In a large skillet saute beef, bell peppers, and garlic til garlic is fragrant (2-3 minutes).
In a small bowl whisk together orange juice, sriracha (2 or 3 tablespoons depending on how spicy you like it), soy sauce, and sesame oil. Add to pan and bring to a boil. Reduce to a simmer and allow to cool for 10-15 minutes until beef is cooked through and peppers are tender.
Whisk together cold water and corn starch. Add to pan and stir to combine. Continue to cook until thickened.
Serve with cooked rice or noodles and top with crushed red peppers if desired.