1.To make batter, mix yeast in a small bowl with 1/4 cup of the beer and stir until dissolved. Add remaining beer.
2.Sift flour and pinch of salt together into a warmed basin, make a well and pour in beer mixture and oil. Stir until blended then leave to rise in a warm spot (for 20-40 minutes). The batter should be risen, well aerated and bubbly.
3.Heat a good depth of oil to 175°C in a sturdy pot (the oil should come one-third of the way up the pot, no more). Dunk pieces of fish in batter one at a time, letting excess drip off, then carefully lower into hot oil; cook in batches.
4.Cook until golden, then flip over and cook the other side. Remove with a large slotted spoon or spatula and drain on a cake rack set over a tray. When all are done, sprinkle with sea salt and serve with kumara chips and lemon wedges.