Heat 1 teaspoon of the olive oil in a large skillet over medium-low heat. Add the onions and cook until soft and caramelized, stirring every 5 minutes, 20 to 30 minutes. Set aside.
In a small bowl, combine the cumin and chili powder. Brush both sides of steak with the remaining 2 teaspoons olive oil and rub the spices thoroughly onto the meat. Heat a grill pan over medium-high heat. Grill the steak for about 4 minutes on each side or until cooked to desired doneness. Rest the steak for 5 minutes and then cut diagonally across the grain into 1/4-inch strips (or thinner, depending on your preference). Wipe the pan clean.
Using the same grill pan, spray both sides of naan with olive oil and place in the pan. Cook on each side, until it starts to char, 2 to 3 minutes. Repeat with second naan.
Lay the naan breads on a baking sheet. Top with the caramelized onions, steak and cheese. Broil until the cheese melts, 2 to 4 minutes. Top with the salsa, avocado, cilantro and some lime juice. Use a pizza cutter to slice, and then serve.