In a medium pot, cover potatoes with 3 inches of heavily salted, cold water. Bring to a boil and cook until knife tender, 10-12 minutes. Drain.
Add potatoes to a large bowl. Mash with a fork or masher. Add tuna, 1 cup of the breadcrumbs, egg, shallot, dill and black pepper, and mix until combined. Scoop ¼ cup of tuna mixture and shape into ¾-inch thick discs.
Toss the tuna cakes in the remaining breadcrumbs.
Line a baking sheet with paper towels. Heat 2 tablespoons oil in a large skillet over medium high heat. Add 6 tuna cakes and cook until golden brown, 4-5 minutes per side. Transfer to prepared baking sheet. Repeat with the remaining oil and tuna cakes. Top with dill and serve with lemon wedges and tzatziki sauce, if desired.
Notes
Storage: These are best served immediately, but you can store leftovers in the fridge in an airtight container for up to 3 days.Freezing Instructions: You can also freeze the individual tuna cakes before or after cooking. Thaw overnight in the fridge before cooking or reheat from frozen if already cooked in the oven at 400°F for 7-10 minutes. They will not be as crisp this way.Substitutes: For best results, follow the recipe as is. However here are some common substitutes that would work well in this recipe.
Instead of canned tuna, you can make these with canned salmon.
Instead of panko breadcrumbs, you can use rolled oats or almond flour.