In a food processor, finely chop but don't puree the fish.
Combine chopped fish, breadcrumbs, onion, celery, and garlic in a mixing bowl.
Whisk together egg, mayonnaise, Dijon mustard, soy sauce, salt, and pepper in a separate bowl.
Gently combine the egg mixture with the fish mixture.
Shape the mixture into desired-sized patties.
Heat vegetable oil in a skillet over medium heat.
Carefully cook patties until golden brown, about 3-4 minutes per side.
Remove and drain patties on paper towels to remove excess oil.
Serve Tanioka fish patties with dipping sauce and side dishes.
Adjust ingredients and seasonings to taste. Enjoy your meal!