In a bowl mix together the Sherry, Minced Gingerroot, Soy Sauce, Honey and Garlic. On top of the stove heat the mixture stirring constantly until the marinade starts to boil. Remove from heat and cool slightly. In a large bowl place the tuna steaks and pour the marinade over top and allowing to cool in the fridge for about two hours. At the one-hour mark make sure to flip the steaks in the marinade. Heat your grill and apply the tuna steaks making sure to frequently baste them with the marinade. Cook the streaks till the outside has been seared and the inside still has a nice pick color to it. Heat the remaining marinade once more to a boil and serve on top of the tuna.