Brush a large heavy skillet with 2 tsp (10 mL) oil and set over medium-high heat. Blend cumin with chili powder, salt and pepper. Rub 2 tsp (10 mL) of the spice mixture over the steak. Sear steak for 2 to 3 minutes per side for medium-rare or until preferred doneness. Remove to a board and tent with foil.

Prepare spaghetti according to package directions.

Meanwhile, add remaining oil, peppers, onion, garlic, and remaining spice mixture to skillet. Stir-fry for 8 minutes or until lightly browned. Slice steak thinly across the grain.

Add hot spaghetti to skillet and toss to combine. Divide between four dishes. Top with sliced steak, diced tomato, diced avocado (if using) and lots of fresh cilantro. Serve each portion with a lime half to squeeze over to taste.