In a large skillet, crumble in the ground beef, and cook for about 3 to 4 minutes, or until it begins to brown, stirring occasionally. Stir in the Mesquite seasoning and onion and continue to cook until the onions are tender and the meat has browned.
Stir in the taco seasoning, salsa and jalapeno. Let simmer over low heat for about 3 to 4 minutes.
Place a tortilla in a large skillet, or griddle, over medium heat. On one half of the tortilla, sprinkle about ¼ cup of cheddar cheese followed by ¼ cup of pepper jack cheese. Top with about a fourth of the meat. Top with ¼ cup of Mozzarella. Fold the tortilla over and press down slightly. Cook both sides until the cheese has melted and the tortillas are slightly browned. Repeat with the remaining ingredients.