I have found most recipes use breadcrumbs as the filler..i prefer mashed potatoes - the taste this way is great. Also note that you can really add whatever tickles your fancy to the mixture - coriander and curry - corn and cilantro - these tuna cakes are so versatile!
2 cans tuna fish
1/2 cup onion, chopped very finely ( you can also cook the onions before adding to the mixture)
2 medium potatoes, boiled and mashed
Fresh parsley, chopped
Garlic, crushed (use as much or as little as you like)
1 egg, beaten well
Salt and Pepper
Flour or breadcrumbs to roll in.
peanut oil for cooking.
Mix all the above!!
Shape into patties.
Roll in flour or breadcrumbs
Fry, turning until both sides are nice and brown.
You could also grill these patties - but i like frying them in peanut oil..nice and light!