Cook the Beef: In a skillet over medium heat, add olive oil. Sauté the onion and garlic until softened. Add ground beef and cook until browned. Drain excess fat. Stir in taco seasoning, salt, and pepper. Cook for another 2-3 minutes, allowing the flavors to meld.

Make the Guacamole: In a bowl, mash the avocados with lime juice. Stir in diced tomato, onion, jalapeño (if using), and salt. Add cilantro if desired. Mix well and adjust seasoning to taste.

Warm the Tortillas: In a separate skillet, warm the tortillas for about 30 seconds on each side until pliable.

Assemble the Tacos: Spoon the beef mixture onto each tortilla. Top with lettuce, diced tomatoes, cheese, and a generous scoop of guacamole.

Serve: Enjoy your tacos immediately with your favorite sides!