MAKE THE LIME CURD: Set a fine-mesh sieve over a bowl. In a small saucepan, cook the eggs, sugar, lime zest, and juice over moderate heat, whisking constantly, until thickened, about 3 minutes. Strain the lime curd into the bowl and whisk in the condensed milk. Cover with plastic wrap and refrigerate for at least 1 hour, until chilled.

MAKE THE MOUSSE: Fill a large bowl with ice water. In a saucepan, cook the egg yolks with 3/4 cup of the cream over moderate heat, whisking constantly, until the mixture has the consistency of yogurt, about 5 minutes. Remove from the heat and whisk in the white chocolate. Transfer to a medium bowl and set it in the ice water to cool completely, stirring occasionally.

In a medium bowl, beat the egg whites with the sugar, cream of tartar, and salt until glossy, soft peaks form. Fold the egg whites into the white-chocolate mixture. In another medium bowl, beat the remaining 1/2 cup of cream until firm. Fold the whipped cream into the white-chocolate mixture with the lemon juice. Cover the mousse with plastic and refrigerate for 1 hour or until chilled.

MAKE THE CITRUS SALAD: In a small saucepan, bring the orange juice, sugar, lemongrass, and ginger to a boil. Simmer over moderate heat until the juice has reduced to 3 tablespoons, about 10 minutes. Strain into a bowl and let cool. Whisk in the honey, lime juice, zest, and mint.

Using a sharp knife, peel the citrus fruits, removing all of the bitter white pith. Working over a cutting board, cut in between the membranes to release the sections. Add to the orange dressing and toss.

Spoon the lime curd into 6 glasses. Using a slotted spoon, divide the citrus salad among the glasses and top with the white-chocolate mousse. Serve right away.