A huge variety of plums come into season in Italy during July. The commercially grown ones are scarcely any better than those available in Britain, indeed are often the same plums from the same cooperatives of growers. The less perfect looking but marvellously flavoursome home-grown plums available from the ‘contadine’ (literally small-holding peasant women) in Orvieto market are another matter altogether.
Cooking plums is difficult, as they often turn incredibly sour or disintegrate, frequently both. This method of baking them with an almost obscene amount of sugar avoids both problems. The plums are sweetened and the juices, comprising water from the fruit and sugar, are soured. This osmotic process achieves an exact balance of sugar, and partially preserves the fruit, so it is best to do quite a quantity. You will need a non-reactive baking dish (pyrex, enamelled metal or pottery), as the extreme acidity of the plums will attack most metals, causing discoloration and a suspect taste.