In a small bowl, whisk together mayonnaise, sriracha, lime juice, and optional garlic. Mix until creamy, cover, and refrigerate to let the flavors meld for about 10 minutes.

In a medium bowl, flake the well-drained tuna, then combine it with the egg, panko, green onions, minced garlic, grated ginger, soy sauce, sesame oil, and black pepper. Stir gently to combine all ingredients evenly.

Divide the mixture into 8 equal portions and shape each into 1-inch thick patties.

Heat oil in a skillet over medium-high heat. Fry the cakes for 3-4 minutes on each side until golden brown and crispy.

Transfer the cooked patties to a paper towel-lined plate to drain off excess oil. Serve these delightful cakes immediately alongside the chilled aioli for dipping.