3 3/4 pints (2 liters) vegetable oil
2 pounds (950 grams) floury potatoes, like russets, peeled and cut into large chips
For the batter:
1 cup plain flour
1 cup beer
2 egg whites, whipped to soft peaks
Salt
4 (9 ounce/250 gram) fillets haddock or cod, skin on, and pin boned