Like many accomplished guy grillers, Paul R. learned some of his technique by osmosis, watching his brother, Guillermo, prepare fajitas for the family. But since Paul is Guatemalan by way of Texas, with a weakness for Chinese cuisine, the family recipe was bound to take a few detours along the way to Pelham, Massachusetts, where Paul now lives. There was dried ginger, not an unexpected addition from someone so fond of spicy foods. Then the Chinese hot chili oil, to crank up the heat - much to the delight, Paul says, of his children, Ana Cecilia, age 21, and Nicolas Zac, 12, both of whom share their father's fondness for zippy flavors. (Paul sometimes even uses a dusting of hot pepper flakes along with the hot oil.) As for the cut of meat, Paul is unequivocal: skirt steak, prized by Central American cooks, he says, for its superior taste and ability to absorb other flavors. "No other meat will do," Paul insists. (We agree, but if you just can't find skirt steak, flank steak is a passable alternative.)
Place the skirt steak in a large, shallow glass or enameled casserole. Generously salt and pepper the exposed surfaces, then sprinkle with 1 tablespoon of the ground ginger. Mash the garlic into a paste - or mince it very fine and spread half of it over the meat. Squeeze one of the limes over the meat, then drizzle on 1 to 1 1/2 tablespoons of the chili oil, spreading it around with the back of a spoon.
Turn the meat over with a fork and repeat the procedure on the other side of the meat. (If you get any of the chili oil on your fingers, be sure to wash them thoroughly with warm, soapy water.) Cover with plastic wrap and refrigerate for at least 2 hours, longer for more intense flavors.
Start your grill and cook the steak over low to moderate heat for about 6 to 7 minutes on each side, turning once, until done to your liking.
Remove the meat to a cutting board. Briefly warm the tortillas on the grill, or in the microwave or oven. Slice the meat thin, across the grain, and place several strips in a warmed tortilla. Add a spoonful of guacamole and/or beans. Roll up the tortilla and serve. Makes 5 to 6 servings.