Cut underside membrane of lobster-tails around edge; remove.
Grasp lobster-tails in both hands; bend backward toward shell sides to crack.
Insert skewers to prevent curling.
Combine all remaining ingredients for sauce; beat until blended.
Place lobster-tails in shallow pan; pour sauce over lobster-tails.
Let stand at room temperature for 1 hour.
Drain; reserve mari- nade.
Arrange lobster-tails on grill 5 inches from source of heat, flesh side down; cook for 5 minutes.
Turn; brush with sauce.
Cook for 3 to 5 minutes longer.
Brush with sauce just before serving.