For the avocado trout spread, cut the avocado in half lengthwise, remove the pit and scoop out the soft flesh with a soup spoon.
On a board, mash the flesh with a fork, mixing with a few squirts of the lemon. Meanwhile, set aside in a bowl.
Now remove the trout fillet from the package and also mash it well with the fork. Add to the avocado in the bowl, add a few squirts of lemon and season with mustard, salt and pepper.