For fish and chips, wash fish, pat dry and cut into bite-sized pieces. Turn to the other side in juice of a lemon.
Put the flour in a large enough bowl, add the egg yolks, beer and salt and mix well. Gradually add the milk mixed with mineral water and mix until a smooth dough.
The dough should be a little thicker than a normal pancake dough. Put the dough in the refrigerator for 30 minutes.
Peel the potatoes, cut them into pieces and dab them on kitchen paper. Heat the deep fryer to 190 degrees. Fry the potato wedges in the hot fat until light brown, remove from the fat and drain on kitchen paper.
Rub the fish pieces dry, season with salt and season with pepper. Dip fish cubes in batches into the batter and bake in the fryer until golden brown. Drain on kitchen paper and keep warm.
Add the potato pieces once again to the hot fat and cook until crispy and golden brown. Also drain on paper towels. Season the potato pieces with salt and bring to the table together with the fish pieces.