In a separate bowl, place the tuna, mayonnaise, Greek yogurt, rice vinegar, and Sriracha hot sauce. Mix well with a fork, and season to taste with salt and pepper. Scoop the tuna on top of the rice and drizzle with more Sriracha if you like things spicy. Add the green onion, avocado, sushi ginger, micro greens, and cucumber as garnishes. Dig in!