Cook ground beef in a large skillet over medium-high heat, stirring until beef crumbles and is no longer pink. Drain well. Remove beef; wipe skillet with a paper towel.
Sauté onion in hot oil in same skillet over medium-high heat. Add chili powder, cumin, salt, and beef. Cook 5 to 7 minutes, stirring occasionally. Stir in beans, tomato sauce, 3/4 cup water, and salsa. Mash pinto beans in skillet with fork, leaving some beans whole. Bring to a boil; reduce heat, and simmer, uncovered, 8 to 10 minutes or until liquid is reduced.
Top evenly with cheese and cilantro. Cover, turn off heat, and let stand 5 minutes or until cheese melts. Serve with taco shells or tortillas and desired toppings.