Peel the mangoes, cut the flesh from the stones and purée it in a food processor or with a hand-held mixer.
Put the wine or water, honey, lemon zest and juice, orange juice and orange flower water, if using, in a saucepan and bring them to the boil. Boil hard until the liquid has reduced to about 3 tablespoons. Allow the mixture to cool slightly, then stir it into the mango purée.
Whisk the egg whites until they form soft peaks, then gradually whisk in the sugar until they are shiny and stiff. Fold the egg whites into the mango mixture. Spoon into individual glasses or one large serving bowl and chill for 2 hours, or until set.