Over medium low heat, roast the garlic cloves (with the skin on) in a pan and cover for 5 minutes or until the garlic is soft and browned on all sides.

Peel the skin off and add the roasted garlic to a molcajete (mortar) with 1 tbsp of salt. Grind to make a garlic salt paste.

Add chopped onion and lightly press with the pestle to release some juices.

Add the vinegar, lime juice, orange juice, olive oil, beer (or ginger beer to make it halal), and spices. Mix well by scraping the bottom of the molcajete to make sure you're incorporating all of the garlic salt paste.

Mix in the cilantro and jalapeno.

Trim off the silver skin membrane and any excess hard pieces of fat, but not too much because fat = flavor. Skirt steak comes in a long strip with the grains running perpendicular to it's length, so I recommend cutting it into 5 inch pieces rather than keeping it whole. For one, it may not fit on your grill in one long piece. Second, it's better to have shorter pieces of steak so that you can get nice uniform slices against the grain once it's ready to serve.

Pour marinade over the skirt steak in a container and massage into the steak. Marinade in the refrigerator for 2-4 hours. Take the marinated steak out of the refrigerator and let it rest at room temperature for 30 minutes before you cook it.

Shake off excess marinade and grill over SCORCHING high heat (at least 600 degrees F) for 3 to 4 minutes per side for medium rare, or 4-5 minutes on each side for medium. The timing will depend on how thick your steak is. I also add the jalapeños to the grill and just use a skillet for the onions. You can also cook it on a cast iron skillet if you don't have a grill.

Let the steak rest for 5 minutes on a cool surface before cutting into it! This is very important, do not skip the resting period.

Cut the steak against the grain and enjoy :)