Heat oil in a skillet over high heat. Add steak strips and cook, stirring occasionally, until cooked to your desired doneness, about 4-6 minutes. Transfer the steak to a plate and set aside.

Set heat to medium-high, and add onions and peppers to the same skillet and season with chili powder and some salt and pepper. Cook, stirring occasionally, until softened.

Serve the steak with the veggies and guacamole.