Dice the pineapple chunks, then mix in a bowl with the cheese and coriander leaves. Butter 1 side of each of the slices of bread, then turn over so the buttered sides are facing down. Divide the cheese mixture between 2 slices. Spread the chilli relish over the remaining 2 slices and sandwich on top, buttered-side up.
Transfer to a sandwich toaster or hot frying pan and cook (turning and pressing down with a fish slice if using a pan) until golden and melted.
