Prepare the Lettuce: Rinse and pat dry your lettuce leaves. Keep them whole if using iceberg or separate them into spears if using romaine. Arrange them on a serving plate or platter and set aside.
Cook the Ground Beef: Heat a large skillet over medium-high heat. Add the ground beef and cook for about 5–7 minutes, breaking it apart with a spatula as it browns. Drain excess fat if necessary.
Season and Add Vegetables: Sprinkle in seasoning salt and black pepper to taste. Add diced onion if desired, and cook for another 2–3 minutes until the onions are soft and the beef is fully browned.
Add the Cheese: Reduce the heat to low. Sprinkle the shredded Mexican blend cheese evenly over the cooked beef. Cover the skillet with a lid and let it sit for about 5 minutes, or until the cheese melts completely and forms a gooey layer over the meat.
Assemble the Lettuce Tacos: Spoon the cheesy ground beef mixture directly onto the lettuce leaves. Be generous with the filling — the melted cheese helps everything stick together perfectly.
Serve and Enjoy: Serve immediately while warm. Roll or fold the lettuce leaves to eat like a taco, or use a fork and knife for a deconstructed “taco bowl” style meal.
