Heat olive oil in a pan over medium heat. Add onion and cook until soft.
Add garlic and ground beef, cook until browned and fully cooked. Drain excess fat if needed.
Stir in taco seasoning and diced tomatoes with green chilies. Simmer for 5–7 minutes until thick and flavorful.
Warm tortillas in a dry pan or oven until soft or lightly crispy.
Fill each tortilla with beef mixture.
Top generously with cheddar and Monterey Jack cheese so it melts over the hot filling.
Add optional sour cream, cilantro, tomatoes, and jalapeños.
Serve immediately with lime wedges.
