Mix mayonnaise with capsicum, carrot and cabbage to make coleslaw. Add pineapple pieces to it. Season well. Apply butter on all the toasted bread slices on one side and on both the sides of four of them.
Place four slices of bread, single side buttered, on a board. Arrange half of the lettuce leaves on them, keep some coleslaw aside for serving as accompaniment and spread the remaining evenly on all the four slices.
Arrange another layer of bread slices, both sides buttered, on it. On this bread slice place the remaining lettuce leaves, tomato and cucumber slices, sprinkle seasoning and place cheese slices.
Cover with the final layer of toasted bread slices, single side buttered. Lightly press with palm to set the ingredients well.
Using a very sharp knife cut the edges of the sandwich and cut it diagonally. Serve with reserved coleslaw and potato wafers.