Season the steak with salt, pepper, chili powder, cumin, and garlic powder. Heat 1 tablespoon of olive oil in a skillet over medium-high heat and cook the steak for 3-4 minutes per side until browned. Let it rest, then slice thinly against the grain.

In the same skillet, add the remaining tablespoon of olive oil and sauté the bell pepper and onion over medium heat for 5-6 minutes until softened. Season with salt and pepper, then set aside.

Wipe the skillet clean, reduce heat to medium-low, and melt 1 tablespoon of butter. Place a tortilla in the skillet, sprinkle half with cheese, layer with sliced steak, and sautéed vegetables. Top with more cheese and fold the tortilla.

Cook the quesadilla for 2-3 minutes until golden brown, press gently. Flip and cook the other side for another 2-3 minutes until crispy and the cheese is melted.

Transfer the quesadilla to a cutting board, let it rest for 1 minute, then slice into wedges and serve warm.