Stir together the lime juice, garlic, soy sauce, orange zest, and red pepper flakes. Put the hens in a resealable plastic freezer bag; pour in the marinade. Seal the bag and toss over so the marinade coats evenly. Place the bag in a bowl in case of leaks. Marinate the hens in the refrigerator at least 2 hours or overnight.
Heat a barbecue grill to medium. Oil the grill. Remove the hens from the marinade. Drain the marinade into a small saucepan, bring to a full boil, and boil for 2 minutes. Place the hens skin side down on the grill. Baste with some marinade. Grill until lightly browned on the underside, about 10 minutes. Use a metal spatula to loosen the hens and turn.
Continue grilling, basting occasionally, and turning and moving as necessary, until no longer pink in the thickest part, 15 to 20 minutes longer. Discard any remaining marinade. This caveat always holds that you discard any marinade that has held uncooked meat.
Contributor: Nigella Davies