For the grapes: Combine the grapes, honey, brandy and lime juice in a zip-top bag, seal and refrigerate for 8 to 12 hours.
For the crust: Process the vanilla wafers, walnuts and salt in the bowl of a food processor for 15 seconds or until finely ground. Add the butter and pulse 6 to 8 times to combine. Press into the bottom of an 11- by 7-inch glass baking dish. Set aside.
For the filling: Whisk the sour cream, brown sugar and vanilla together in a large mixing bowl. Drain the grapes and reserve the liquid for another use. Add the grapes to the sour cream mixture and stir gently to combine. Pour the grape mixture on top of the crust and set aside.
For the topping: Combine the brown sugar and butter in a 1-quart saucier and place over medium-high heat. Bring to a boil, stirring constantly. Stir constantly and boil for 1 minute. Remove from the heat and pour over the grape mixture. Do not stir into the sour cream mixture. Cool at room temperature for 5 minutes, and then sprinkle the sea salt on top. Chill in the refrigerator for 1 hour before slicing.
Cook's Note: You may use the reserved grape liquid to mix with your favorite adult beverage for a cocktail or with soda water for a refreshing non-alcoholic drink.