Preheat the oven to 200*C.
Put the potato, almond flour and egg whites in a food processor and mix it well. It will resemble a very thick soup!
Pour out into a bowl and then stir in the tuna to mix. Now add any of your creative additions (chopped red onion would be really nice.. or even cranberries, olives, shredded cheese (if you fancy dairy), or whatever!).
I used an ice cream scoop to make these perfectly formed balls. But you can just plop them on a lightly greased baking pan however you want. (I recommend the ice cream scoop though...)
Bake for about half an hour until they are firm to the touch.
Really really nice reheated in the oven! (I don't know about a microwave - as I don't have one... but I like the crispness of the outside contrasting with the moist 'doughy' centre...)