1) In a wide, shallow glass baking dish, scatter half of the orange slices, half of the onion slices and half of the garlic pieces on the bottom of the dish. Sprinkle the steak all over with salt and pepper and put in the dish on top of the orange and onion slices. Scatter the remaining orange, onion and garlic over the steak and pour in the beer and soy sauce. Cover with plastic wrap and marinate for one hour at room temperature or up to overnight in the refrigerator.
2) Prepare a barbecue on medium-high heat or preheat a grill. Remove the meat from the marinade and discard the marinade. Grill the steak to desired doneness, about 4 minutes per side for medium-rare. Serve as desired.
Notes Grilled skirt steak sliced into strips is a great filling for tacos. Top with shredded cheese and beans, or use your favorite taco filling!