In a skillet over medium heat, add 1 tablespoon of oil and sauté the finely chopped onion until softened and translucent, about 2-3 minutes. Then, crumble in the ground beef and cook until browned and no longer pink, about 4-5 minutes.

Mix in tomato paste and taco seasoning, stirring well. Add water or beef broth, let simmer until thickened, about 3-4 minutes. Taste and season with salt if needed, then cool slightly.

Lay a tortilla flat, sprinkle shredded mozzarella on the top half. Spoon some beef filling over the cheese, add more cheese, then fold the tortilla to seal.

Heat oil in the skillet over medium heat until shimmering. Fry each assembled taco for about 1 minute per side until golden brown and crispy. Drain excess oil on a wire rack.

Garnish fried tacos with chopped cilantro and serve immediately.