Drain the oil from the can of tuna, place the contents in a bowl, and flake with a fork.
Add mayo and crème fraîche alternately a little at a time, working them in with the fork until the desired consistency is reached. I prefer it not to be too "wet," but that's a matter of taste. Add corn and peas and fold into the mixture.
Add lemon juice to taste; I add just a little to give some acidity without making it taste too much like lemon.
Some choose to add spring onions or regular onions to the recipe, but I prefer the soft taste that mayo and crème fraîche provide on their own.
Instead of paprika, you can sprinkle with chili powder or flakes, which also suit the dish well.