Using a channel knife, cut a few grooves into the orange peels. Cut the tops off the oranges and reserve. Empty the entire fruit of the orange pulp, being careful not to create a hole in the bottom. Freeze the empty orange rinds to create shells.
In a bowl, combine the egg yolks with 1/2 cup of the sugar and beat until thick and a pale yellow. If using an electric mixer, mix for 5 to 7 minutes. Add the lemon curd or marmalade, orange liquer, and vanilla. Mix well.
In a separate cold bowl, whip the cream until firm. Set aside.
In another bowl at room temp, beat the egg whites until soft peaks form.
In a large stainless steel bowl, blend the whipped cream and the egg yolk mixture. GENTLY fold in the egg whites. Transfer the mixture to a pastry bag fitted with a large tip. Remove orange shells from freezeer and pipe the mixture into them, extending 1 inch higher than the top of the orange. Freeze for at least 4 to 5 hours. Add the tops and serve right out of the freezer with Lime and Yogurt Sauce.
Lime and Yogurt Sauce:
Mix all the ingredients in a food processor until very smooth.
Consumption of raw or undercooked eggs, shellfish and meat may increase the risk of foodborne illness.