Add the rice to a sauce pan along with 3 cups of water and a generous pinch of salt. Bring the mixture to a boil, then reduce heat to low, cover, and simmer for 9-11 minutes, or until the water is all soaked up and rice is tender. Remove from heat and set aside.
In a medium bowl, whisk together the soy sauce, rice vinegar, honey, garlic, and ginger. Toss it with the tuna. Add the tuna to a skillet and cook over medium high heat for 2-3 minutes. Remove from heat.
In another small bowl, whisk together the mayonnaise, Sriracha, and lime juice, to taste.
To make the bowls, divide the rice evenly between four bowls. Top with the tuna, cucumber slices, and avocado. Sprinkle with green onions and toasted sesame seeds. Drizzle with spicy mayo and serve with pickled ginger, if desired.