Add all the ingredients except the oil to a food processor with a pinch of salt and blitz until smooth. Transfer the batter to a jug, cover with cling film and leave to rest in the fridge for 1 hr.
Heat oven to 220C/200C fan/gas 7. Spoon a tsp of oil into eight holes of a muffin tin and place in the oven for 5 mins to get really hot. Remove the tin from the oven and carefully pour the batter into the hot oil. Return to the oven and bake for 25-30 mins until risen and deep golden brown.