In a food processor add the cilantro, quartered onion, juiced limes, garlic, oil, jalapeños, salt and pepper. Blend until smooth.
Preheat grill to 350-400°F.
Pour this mixture into a Ziploc bag or container that can seal and add the skirt steak pieces. Seal and let marinate at room temperature for 30 minutes.
Clean grill and oil. Grill 3-4 minutes per side for medium rare. 5-6 minutes per side for medium. Allow to rest 5 minutes before slicing AGAINST the grain.
Video
Notes
I use Mexican limes, which are typically thin skinned, slightly yellow and extra juicy. They are sometimes called Key Lime and have a higher acidity. Feel free to use regular limes if unavailable.