Place the flour in a bowl. Make a well at the center and pour in the beer. Mix to make a rather thin batter with the consistency of pancake batter. You may need to add more flour or beer to get the right consistency.
Add salt and pepper. Stir in the yeast. Leave for the yeast to become active, about 30 minutes.
Dab with paper towels to remove excess moisture as the batter will not stick properly to the fish if it is wet.
Start heating the cooking oil. The ideal temperature is 350F.
Dip each piece of fish fillet in the batter.
Fry until golden, flipping over for even cooking. This should take about a minute or two for each side.
Remember not to overcrowd the pan. Fry only one or two pieces at a time.
As each piece of fish cooks, scoop out of the oil and transfer to a plate lined with paper towels to get rid of excess oil.
Arrange your fish and chips on a plate. Serve at once with the mayo-ketchup dip (mix equal amounts of Japanese mayo and tomato ketchup) on the side.