Begin by cutting the sashimi-grade Ahi tuna into ¼-inch dice and placing it in a medium mixing bowl. In another small bowl, whisk together the soy sauce, rice vinegar, sesame oil, grated fresh ginger, and a pinch of sesame seeds. Pour the marinade over the diced tuna, gently tossing to coat. Let the mixture rest for 5 minutes, allowing the flavors to meld, or refrigerate for up to 1 hour for a more intense flavor.

While the tuna is marinating, take the seedless cucumber and slice it thinly into rounds, about ¼-inch thick. Arrange these cucumber slices neatly on a serving platter, making sure they are visually appealing and ready to hold the delicious tuna poke atop them.

In a small bowl, combine the mayonnaise with the Sriracha sauce, adjusting the amount of Sriracha based on your preferred level of heat. Stir well until the sauce is smooth and creamy.

Take a spoonful of the marinated tuna poke and place it atop each cucumber slice on the platter, allowing the colorful tuna to spill slightly over the edges.

Drizzle the spicy Sriracha mayo over each tuna poke bite, giving them a beautiful finish. Finally, sprinkle with sesame seeds, and add any optional garnishes you desire.