Wash capsicum, then remove seeds and membranes. Using a food processor, chop finely. Transfer to a colander over a plate. Sprinkle with salt. Let stand 1 hour. Rinse under cold water.
Place capsicum, sugar, vinegar and 1/2 cup water in a large heavy based frying pan. Cook and stir over moderate heat for 5 minutes or until sugar dissolves. Bring to the boil. Reduce heat; simmer, uncovered, for 30 minutes or until mixture thickens. Let cool.
To serve, top slices of bread with cheese, ham and Capsicum relish.