Heat medium non-stick skillet over medium high heat. Add chorizo to skillet (no need to add oil), and cook until crisp, stirring occasionally; set aside in small bowl.
Add onion, garlic, and corn to same skillet where chorizo was cooked and sauté for 4 minutes in remaining chorizo fat. Season with cumin, salt, and pepper. Divide mixture evenly into 4 portions.
Warm tortillas for 10 to 15 seconds on each side on an ungreased pan.
Assemble the tacos by filling the tortillas with chorizo, corn mixture, cheese, and avocado slices. Serve with Pico de Gallo salsa, if desired.