1.For the profiteroles, put the water in a saucepan with the butter and a pinch of salt. Add the flour when the water begins to boil and the butter is diluted.
2.Mix with a wooden spoon until forming a paste. Keep it on the heat until the dough is dry and comes off easily from the container. At that point, remove from the heat and let it cool.
3.Add 1 egg; The dough will separate and must be stirred until it comes back together and is completely integrated. *Repeat with the rest of the eggs.
4. Transfer the dough to a pastry bag and form walnut-sized balls on a greased baking tray. Bake for 15 to 20 minutes at 210ºC.
5.Meanwhile, add the mustard and a tablespoon of dill to the sour cream and add salt to taste.
6.Open the profiteroles in half (without separating them) and fill them with a tablespoon of sour cream; Distribute some capers, a small piece of smoked salmon in each one and a sprig of parsley to decorate.