Line two bread pans, approximately the same size as the angel food cake, with plastic wrap. Soften sherbet. Scoop lime sherbet into one pan and raspberry sherbet in the other. Spread sherbet with a metal spatula dipped in hot water. Sherbet should be approximately 1/2 inch deep. Refreeze sherbet in pans for at least 1 hour or until hard.
Trim edges of angel food cake with a serrated knife to even them; cut cake into three lengthwise slices.
Remove frozen lime and raspberry sherbet from freezer. Alternate layers, cake, sherbet, cake, sherbet and cake. Cut off any oversized sherbet or cake to ensure that cake and sherbet are even on all sides of the cake. Refreeze until solid; can be frozen up to 3 days if wrapped well in plastic wrap.
Before serving, prepare cake topping by whipping the cream until very thick. Add sugar and lemon juice and whip mixture until soft peaks form. Spread whipped cream on cake. Refreeze cake until ready to serve.
Remove cake from freezer and let soften 5 to 10 minutes. Slice with an electric knife. If desired, place cake slices on pools of strawberry or raspberry sauce and top with a lemon twist and mint leaves.