Place all the ingredients, except for the beans, oil and lime wedges, in a food processor with ¾ teaspoon salt. Blitz roughly so that most (but not all) of the sweetcorn is broken up. Stir in the sliced beans.
Add 2 tablespoons of oil to a large frying pan and place on a medium-high heat. Once hot, add 4 tablespoons of the mixture to make 4 fritters; do this carefully as the oil will spit. Flatten the mixture down so that each fritter is about 6 or 7 centimetres wide and 1½ centimetres thick and then fry for 1-2 minutes until golden-brown on the bottom (this is important: they need to crisp up completely on the bottom for them not to break when you turn them over; add a little extra rice flour if this still happens). Use a spatula to carefully turn the fritters over and fry for another 1-2 minutes. Transfer to a kitchen paper-lined plate, sprinkle with a pinch of salt and keep somewhere warm whilst you continue with the remaining mix in the same way, topping up the oil with an extra tablespoon for each batch. Serve warm with and the lime wedges alongside.