Rinse chicken breasts in cold water and pat dry with paper towel.

Cut chicken breasts in half lengthwise making 2 large strips.

Salt and pepper chicken and let set for a few minutes before adding marinade.

Pour 1/4 cup Ancho Chile Marinade into a prep dish, adding more as needed.

Generously brush chicken breasts with marinade on both sides and set in shallow dish.

Let chicken rest with marinade for up to 30 minutes. If you want to do this longer, then pop in fridge until ready. If it's going to be more than an hour, cover or place chicken breasts in large baggie with marinade and rub it around to coat the chicken. (This is not an overnight marinade!)

Sear on direct high heat for about 2 minutes on each side, remove from direct heat and cook slowly over indirect heat for about 6 minutes, turning a couple of times.

Remove to plate, cover with foil and let rest while you prepare the onions and tortillas.

Heat 1 tablespoon of olive oil in a sauté pan on medium high heat.

Add marinaded chicken breast pieces, scraping sauce into pan.

Sauté on both sides until cooked through, about 6-10 minutes total, set on a clean plate and cover with foil while you make the onions.

Heat clarified butter or olive oil in sauté pan on medium high heat, add onions and toss around.

Sauté for about 5 minutes only, stirring a few times. You want them limp but still a little crunchy.

Turn the heat up a bit, add 1 tablespoon of apple cider vinegar and stir until vinegar evaporates.

Lightly salt and pepper to taste.

Slice chicken into thin strips or pull apart with 2 forks to shred. If chicken has cooled or you make it ahead, reheat in pan with meat juices poured in or add a couple tablespoons of water and a tablespoon of extra sauce. Stir to reheat and shred in pan with two forks.

Serve warm corn tortillas with chicken, queso fresco crumbled, warm onions, cilantro leaves and a chipotle salsa if you wish.