Roll fish cubes in the combined
garlic, lime juice, sesame seeds and oil and marinade for 30
minutes. Thread fish and tomatoes
alternately onto skewers, grill under moderate heat for 3 minutes
each side, basting regularly with the marinade. Melt the butter in a medium
saucepan over moderate heat. Add onion, cumin, coriander,
sherry, sesame paste, honey, peanut butter, lime juice and water;
cook for 5 minutes, stirring constantly or until sauce thickens. Serve kebabs with sesame sauce.