You may have one or two pieces of fish left over from making crusted cod. Here’s what I did with my leftovers the next day. I toasted sandwich buns and spread them with tartar sauce. Add the fish and voila! A tasty fish sandwich for lunch.
As for leftover mashed potatoes, you can freeze them, but I always turn them into breakfast patties. I stir in one egg, some grated cheese, herbs, maybe some onion and a handful of bread crumbs. Form the potatoes into small patties and coat with more breadcrumbs. It’s helpful, but not required, to firm the patties up in the freezer for a few minutes. Shallow-fry in a little hot olive oil until golden-brown. These patties are especially good topped with a poached egg or with flaked, smoked salmon mixed in.