In a large china or glass bowl, mix together all the marinade ingredients. Carefully stir in the tuna, cover and marinate the fish in the refrigerator for at least 30 minutes, or up to 12 hours.
When ready to cook, heat the grill to its highest setting. Remove the tuna from the marinade and divide it between eight skewers.
Grill the kebabs for 5-6 minutes, basting frequently with the remaining marinade and turning them over a few times so that the fish is evenly cooked and flakes easily. Garnish with lime wedges and coriander.
Tip: if using bamboo or wooden skewers, soak them in cold water for 30 minutes beforehand.