In a skillet over medium heat, cook chicken for 5-7 minutes, or until it reaches 165° F. Add chipotle salsa and simmer for 2-3 minutes until chicken is coated and sauce is reduced slightly.
Heat the tostada shells according to package instructions.
Top each tostada shell with avocado salsa, cooked chicken, corn kernels and cotija cheese. Garnish with Tajin seasoning and fresh cilantro.