Gather all your ingredients.
Put the mackerel, half the pack of cheese (125g), horseradish and the juice of 1/2 lemon into a food processor. I generally use a 2:1 ratio of fish to cheese so you can scale up or down as necessary.
Blend until you get to the texture you prefer. You can also do this in a bowl with some vigorous mashing with a fork if you don't have a blender.
Scrape into a bowl and scoff. If you want to be fancy you can serve it in a jar with some bread you've toasted on a griddle!
TOP TIP! - obviously I've used mackerel here but you can just as easily swap it out for smoked salmon or trout. Also if you use Quark cheese it's pretty much fat free too!