Heat the skillet over medium-high heat until it’s hot and slightly shimmering, then add the ground meat. Cook, breaking it apart with a spatula, until browned and fragrant, about 8 minutes.
While the meat cooks, chop the onion into tiny pieces and dice the tomatoes if using fresh; set aside.
Add the chopped onion to the skillet with the meat and cook until translucent, about 2-3 minutes, allowing the flavors to meld.
In a small saucepan, combine the diced tomatoes, a squeeze of lime juice, and a pinch of salt. Bring to a gentle simmer over medium heat and cook until the salsa thickens slightly, about 10 minutes, stirring occasionally.
Once the meat mixture is cooked and the salsa has thickened, remove both from heat. Warm the tortillas in a dry pan over medium heat for about 30 seconds per side until soft and pliable.
Fill each tortilla with a generous spoonful of the browned meat, then spoon over some of the fresh salsa.
Sprinkle the shredded cheese evenly over the filled tacos, then place them back in the skillet or in the oven just until the cheese melts, about 1-2 minutes.
Squeeze a little lime juice over each taco for brightness and garnish with chopped cilantro if desired.
Serve the tacos immediately, with the melted cheese oozing and the toppings bright and fresh, perfect for a playful Halloween feast.
