Rub lamb with Greek seasoning and refrigerate, covered for 2 hours.
In a large shallow dish, whisk Greek seasoning, vinegar, olive oil, lemon juice and Braggs. Add lamb and turn to coat. Refrigerate, covered, 4-6 hours or overnight, turning once or twice.
In a small bowl, mix mint, pepper jelly and hot water until combined. Refrigerate, covered, until serving.
Preheat grill to medium-high heat.
Discard the marinade from the lamb dish. Cover rib ends of the lamb with foil. Grill on an oiled rack, covered, for 2 minutes on each side. Turn and move to indirect heat. Coo, covered until meat reaches desired doneness (135°F for medium-rare to 145°F for medium-well), about 25-30 minutes. Let stand for 10 minutes.
Serve with Jalapeno-Mint sauce; sprinkle with oregano, chives and additional mint if desired.