1.Preheat oven to 180°C (160°C fan-forced).
2.To make salsa, combine tomato, capsicum, onion, coriander, olive oil, juice and chilli in a small bowl; season to taste.
3.Remove oysters from shells; reserve oysters. Place shells on an oven tray; heat in oven for 5 minutes.
4.Meanwhile, combine polenta, milk, egg and cayenne pepper in a small bowl.
5.Heat vegetable oil in a medium saucepan. Dip oysters in polenta batter; deep-fry oysters, in batches, until browned lightly. Drain on absorbent paper. Return oysters to shells; top with salsa to serve.