Slice the chicken breasts starting with the thick side almost in half, then open like a book.
Place each open breast between two pieces of plastic wrap, wax paper or inside a large, open, Ziploc bag.
Using a rolling pin or a small heavy pan, pound out each breast into even thickness.
In a small bowl, mix the marinade/sauce ingredients. Reserve 1/2 the marinade for the sauce.
Add chicken and marinade to a large bowl and chill in the refrigerator 1 hour or overnight.
Once you are ready to cook the chicken, remove each breast from the marinade and discard the marinade.
Pour the reserved sauce into a small saucepan and bring to a rolling boil. Boil continuously for at least 2 minutes, stirring occasionally so it doesn’t burn.
In a heavy skillet or grill pan, heat a splash of oil over high heat.
Cook the chicken in batches to prevent over crowding the pan.
Place the breasts in the hot pan and cook without turning for a couple minutes
Flip the breasts over and cook until the other side is golden, it shouldn’t take long depending on the thickness of your chicken.
Place cooked breasts on a plate in a warm oven or under foil while cooking the remaining chicken.
Sprinkle with fresh lime juice and cilantro. Serve with sauce on the side.