Rinse the conch to remove any grit, then pat it dry and pass it through a grinder or food processor. Mix together the ground conch, scallion, celery and onion. Add the tomato paste, lemon juice and red pepper. Let stand for about 10 minutes, then stir in the flour and baking powder along with enough water to make a thick batter.
In a frying pan, heat the oil until a spoonful of batter dropped into the oil rises to the surface. Place 2 tablespoonfuls of batter in the hot oil at a time, cooking until the fritters are golden brown on all side. Drain on paper towels.
Serve hot, 2 fritters per serving with cocktail sauce or salsa for dipping. Serves 6