1. Mix 1 teaspoon of salt and 0.5 teaspoon of sugar. Sprinkle the mixture over the cod fillets and leave to marinate for 20 minutes.
2. Heat the oil in a saucepan to 170 degrees.
3. Prepare the batter: mix flour, baking powder and starch. Gradually pour in the egg yolk with ice water. Stir until a homogeneous consistency is obtained.
4. Cut the cod fillet into portions with a side of about 3 cm.
5. Dry the fish with a paper towel from excess moisture before frying.
6. Dip the pieces of fish in the batter and immediately dip them in hot oil. Fry until golden brown (about 2-3 minutes).
7. Put the pieces of fish on a paper towel to drain the excess oil.
8. Serve hot.