Peel and section the fruit into a bowl, squeezing out all of the juice. Measure out 3/4 cup/175 ml of juice and put it in a saucepan with the wine. Add the sugar and heat to dissolve. Pour 1/4 cup/60 ml off into a bowl and soften the gelatine in it one minute. Return it to the pan. Stir to dissolve, and boil 2 minutes. Cool completely.
Line a 1-quart/1-litre terrine or glass loaf pan with plastic wrap, leaving enough overhang to cover the terrine afterwards. Arrange the fruit decorative in the terrine. Pour the liquid over. Chill terrine, covered, until firm, at least 4 hours, and up to 2 days. Garnish with mint sprigs or candied orange zest.