Meringue: Heat the oven to 300 Celsius. Beat the egg whites until stiff peaks form; keep beating while adding icing sugar to taste, lime zest and cream of tartar continue beating until getting a stiff consistency. Tip them onto a previously greased baking sheet sprinkled with flour. Bake for about 7 minutes then reduce temperature to 100 Celsius. Turn the oven off completely when they start to go brown (not burnt). Leave them in for a little while.
Sauce: Melt butter in a saucepan, add jelly and rum; simmer until a light sauce is formed.
Cream: Whip the cream until getting a puffy consistency, stir in sugar and cranberries, pour sauce over the meringues and decorate with mint leaves.