3 -- sole fillets, around 5 oz each, coarse chopped
1/2 teaspoon dry mustard
1/2 teaspoon red pepper flakes
1/2 teaspoon dried thyme
1/2 teaspoon Old Bay
1 -- egg, beaten
1 cup leftover mashed potatoes or loose hashbrowns
3/4 cup dry bread/cracker crumbs
2 cups vegetable oil
to taste -- tartar sauce or soy vinegar
Place chopped vegetables in a food processor; pulse to finely chop. Add the fillets; pulse to coarsely chop. Stir in salt, pepper, mustard, pepper flakes, thyme and seafood seasoning; pulse 2 to 3 times until mixed. Transfer to large bowl; stir in the egg, stir lightly to combine. Fold in the potatoes.
Form into 8 patties and lightly coat with breadcrumbs.
Heat oil in a skillet over medium-high; add the cakes. Cook until lightly browned on one side, about 4 minutes. Turn; cook until browned and cakes are cooked through, about 4 minutes.
Serve with tartar sauce or sprinkled with vinegar.