Let's start out by marinating the chicken. This marinade is really potent, so you don't need a lot of time to add great flavor. An hour will do it, 2 hours are even better. Throw all of the marinade ingredients into the food processor, pulse and then pour it over the chicken breasts in a bowl.
Let the chicken marinate for at least an hour, up to 3 hours, flipping the breasts once. The last 30 minutes should be on the counter at room temperature.
While the chicken is marinating, chop up your cilantro and slice the onion into thick slices. Try to keep all of the rings together so you don't have to chase onions around the grill.
Heat the tomato sauce in a pot until it just starts to boil and then turn the heat down to low to slightly simmer.
Add all of the spices to the sauce and stir well.
Adjust the spices to taste. Enchilada sauce has a hint of cinnamon and I like mine with a little heat. Adjust to your liking…
Now that the chicken has been marinating for an hour, let's move the party outside and fire up the grill!
Heat one side of the grill to medium heat, while leaving one burner on the other side completely off. The cool side will become our heating station for the tortillas. Heating them on the grill will allow us to pick up a little additional smoke taste from the chicken.
Grill the chicken over the hot (medium) side of the grill with the lid closed while cooking.
At the same time, grill the onions to soften them slightly and create some good grill marks.
Once the chicken has cooked through, the onions are slightly softened and the tortillas are warm, let's move it back to the kitchen.
Slice or pull the chicken into thin pieces and place into a bowl.
Dice the grilled onions and add them to the bowl with the chicken.
Add your cilantro and cumin to the bowl and we've got an enchilada fiesta!
Taste the filling in the bowl. Want a little heat? Add some cayenne. Not salty enough? You know what to do…
Ladle enough sauce into a casserole dish to cover the bottom of the dish, just enough so that the tortillas don't stick.
Scoop some of the chicken filling into each tortilla, roll the tortilla and place it with the fold down into the dish, on top of the sauce.
Once you've used all of the chicken filling (or ran out of room), pour the rest of the sauce over the top of the enchiladas.
Layer on some shredded Monterrey Jack cheese and place under a broiler until the cheese has browned slightly.
Serve with some rice and enjoy!