Combine the marinade ingredients in the food processor or mixing bowl.
Place steaks in baking dish. Make 1/4" cuts 1" apart to allow marinade to soak into the meat. Combine ingredients and pour over steak. Allow to marinate covered for 4-8 hours.
Heat grill or stovetop to medium high. Add steak and cook 4 minutes. Flip and cook 4 minutes or until it reaches the desired temperature.
Remove from heat, cover and allow to rest at room temperature 10 minutes.
Slice thin across the grain.
Serrano Avocado Salsa
In a food processor, combine tomatillos, serranos, avocado, cilantro and lime juice. Pulse until smooth.
Assemble tacos adding steak, chihuahua cheese and serrano sauce and an optional squeeze of fresh lime.
Notes
Allow time to marinate the steak at least 4 hours or up to 24.
If you use corn tacos, heat them gently in the oven for a couple of minutes or stove top for 30 seconds each side to warm before serving so that they don't break when you fold them.
Allow it to rest for 10 minutes before slicing it across the grain.