First make the chilli jam. Roughly chop the tomatoes, chillies and garlic cloves, then put in a food processor and process until fairly smooth. Transfer to a saucepan and add the remaining ingredients. Bring to the boil, then reduce the heat and simmer gently, stirring occasionally to prevent the sauce sticking, for 30–40 minutes until thick and jam like. Set aside to cool completely.
Put half the sweetcorn in a food processor and process until fairly smooth. Sift in the flour and baking powder and add the egg, soy sauce and lime juice. Process again until combined and transfer to a bowl. Stir in the remaining sweetcorn, lime leaves and coriander.
Heat the oil in a large frying pan. Drop in 6 separate tablespoonfuls of the batter, pat them flat and fry over a medium-high heat for 1½ minutes on each side until cooked through. Repeat with the remaining batter to make 12 x 5 cm (2 inch) fritters. Serve the fritters hot with the chilli jam, garnished with lime wedges and coriander sprigs.