Ahi Tuna Tartar with Wasabi Caviar and Spicy Ginger Vinaigrette

Name: Ahi Tuna Tartar with Wasabi Caviar and Spicy Ginger Vinaigrette
Ingredients: 1 pound sashimi grade Ahi tuna, finely diced; 1/4 cup Sake and Sesame Marinade, recipe follows; 1/4 teaspoon sesame seeds, toasted lightly; 1/4 teaspoon black sesame seeds; 1 avocado; 1/2 cup diced pineapple; 1/4 cup sesame oil; 1/2 teaspoon chopped garlic; 1/2 teaspoon chopped shallot; 1/2 teaspoon fresh chopped ginger; 1 cup sake (rice wine); 1/2 cup rice vinegar, unseasoned; 1/4 cup soy sauce; 1/3 cup brown sugar, or to taste; Cornstarch slurry (3 tablespoons cornstarch and 1 tablespoon water, blended), to thicken