How to Make It
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.
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.
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.