Heat a indoor or outdoor grill to medium high and grease the grates with a little bit of olive oil. Season the lamb crossbones with salt and pepper to taste, and grill for 7 minutes on each side for medium-rare, or until they have reached your desired doneness.
Dress the watercress with lemon juice and olive oil and season with salt and pepper to taste. On a plate, add a spoonful of the barley, then top with a crossbone. Garnish with 1 cup of the watercress salad.