How to Make It
Preheat the oven to 425°. In a small saucepan, combine 1/4 cup of the granulated sugar with the red currants, water, orange zest, and lemon zest. Cook over low heat for 5 minutes, then boil over moderate heat until the mixture starts to thicken, about 8 minutes. Strain the sauce through a fine sieve, pressing hard on the solids to extract the juices. Boil down the sauce to 1/3 cup, about 5 minutes. Let cool.
Lightly coat four 5-ounce ramekins with vegetable spray. In a medium bowl, stir together the red currant sauce, yogurt, flour, and vanilla.
In a separate medium bowl, beat the egg whites until they hold soft peaks, then gradually beat in the remaining 3 tablespoons of granulated sugar until the whites are stiff but not dry. Fold half of the egg whites into the yogurt-red currant mixture with a whisk, then gently fold in the remaining egg whites using a rubber spatula. Spoon the mixture into the prepared ramekins until it just reaches the top.
Transfer the ramekins to a baking sheet and bake on the lowest rack of the oven for about 12 minutes, or until they are well risen and light brown on top. Dust the tops of the soufflés with confectioners' sugar and serve at once.