Lime and garlic, with a bit of soy sauce, are a perfect and easy marinade for skirt steak.
In blender, combine lime juice, soy sauce, garlic, and jalapeno; puree until smooth. Transfer to a shallow dish or large resealable plastic bag. Toss with steak to coat. Let stand at least 30 minutes, and no more than 2 hours, to infuse with flavor.
Heat a large skillet over medium-high, until very hot. Cook steak, in two batches if necessary, until browned, 2 to 3 minutes per side for medium-rare. Let rest 10 minutes before slicing thinly. Serve with lime wedges, if desired.
Fresh limes will last about 10 days in the refrigerator.