In a small bowl, combine onion and cilantro; set aside.

Coat a medium skillet with nonstick cooking spray. Heat pan over medium heat. Add garlic to pan; cook until just starting to brown, about 1 minute, stirring constantly. Stir in enchilada sauce, chicken stock, chile powder, cumin, and salt. Bring to a boil over medium-high heat. Add chicken to pan; cover, reduce heat to medium-low, and simmer until chicken is cooked through and tender, 17 to 20 minutes.

Remove chicken from pan with a slotted spoon to a cutting board. Shred chicken with 2 forks and place in a medium bowl; stir ½ cup sauce into chicken, and reserve remaining sauce in skillet.

Coat a large nonstick griddle with nonstick cooking spray and heat over medium-high heat (or coat 1 to 2 large nonstick skillets with nonstick cooking spray and heat over medium-high heat). Working in batches and working quickly, dip 1 tortilla into sauce, coating both sides with sauce. Arrange on griddle or skillet and repeat with as many tortillas as will fit. Cook until browned on bottom, 2 to 3 minutes. Carefully lift tortillas with a spatula and flip over. Sprinkle 1½ tbsp cheese over half of each tortilla; top with about ⅓ cup chicken mixture. Cook until browned on bottom, 2 to 3 minutes. Fold empty side of each tortilla over filled side to close taco; remove tacos to a plate and repeat with remaining ingredients. Serve tacos with onion mixture and lime wedges.

Serving size: 2 tacos and ¼ cup onion mixture