In a large bowl, combine the flaked tuna, breadcrumbs, green onions, red bell pepper, egg, soy sauce, sesame oil, garlic powder, ginger powder, salt, and pepper. Mix until well combined.
Form the mixture into patties, about 2-3 inches in diameter. You should get about 6-8 patties.
Heat the vegetable oil in a large skillet over medium heat. Once hot, add the tuna cakes in batches, being careful not to overcrowd the pan. Cook for 3-4 minutes on each side, or until golden brown and crispy.
While the tuna cakes are cooking, prepare the spicy mayo by mixing together the mayonnaise, sriracha sauce, and lime juice in a small bowl. Adjust the spiciness to your preference.
Once the tuna cakes are cooked, remove them from the skillet and place them on a paper towel-lined plate to drain excess oil.
Serve the tuna cakes warm with a drizzle of spicy mayo on top or on the side for dipping.