Remove the peel carefully from the fruit, if possible in quarters. Put the peel into a pan with enough water to cover and simmer for 1½ hours, adding more water if necessary. Add 2 oz/50 g sugar for each fruit used and stir until dissolved. Bring to the boil, then put aside without a lid until the next day. On the next day, bring to the boil and simmer for 5 minutes. On the following day, simmer until the peel has absorbed nearly all the syrup. Drain the peel and put on paper on a wire cake rack. Cover with greaseproof paper and dry slowly. A little syrup can be poured into the hollow of the peel pieces.