1. Sprinkle a little salt on the fish fillets. Dissolve yeast in two tablespoons of warm milk. Keep it in a warm place.
2. Add salt and mix. Mix together half cup of refined flour, corn flour, baking powder and salt well. Add egg yolk to the yeast mixture and mix. Add this mixture to the flour and whisk. Add milk and continue to whisk well to make a thick and smooth batter.
3. Cover and rest it for one to one and a half hours to ferment slightly.
4. Heat sufficient oil in a deep frying pan. Roll the fish fillets in the remaining refined flour. Shake away excess flour.
5. Dip them in the batter and deep fry in hot oil till golden. Drain and place them on an absorbent paper.
6. Serve hot with tartare sauce.