Place the yolks of 4 boiled eggs, Vegetable oil, mustard, horseradish and lemon juice in a bowl.
I took mustard seeds, you can use any to your taste. The main thing is that it is not very sharp, otherwise the pate will be with a clear taste of mustard
Combine everything together in a homogeneous mass with an immersion blender
I used canned saury. You can use any natural canned fish (without tomatoes) - pink salmon, mackerel, sardine, tuna, etc.
Mash the canned fish, first draining the liquid.
Add the egg whites grated on a fine grater and boiled carrots. Here, add the butter-yolk mass from step 1. Season with pepper.
Mix everything until smooth. Canned fish contain a sufficient amount of salt,and I did not add salt to the pate. You look to your taste, if necessary, add salt.
This pate is not very uniform texture, slightly rough, I would say. If you want a more uniform pate - grind everything with an immersion blender into a single mass.
Sandwiches can be supplemented with a thin slice of lemon or pickled cucumber.
You can use this pate just on sandwiches or serve it, for example, as a sauce for baked potatoes in the skin, which will also be delicious.