In a medium saucepan, mix sugar and cornstarch. Stir in milk, lemon rind and juice until sugar is dissolved. Add margarine. Stirring over medium heat, bring to a boil and boil for 1 to 2 minutes or until thickened. Remove from heat.
Gradually stir about one-third of the hot mixture into the egg yolks, then stir back into hot mixture in saucepan. Cook and stir over low heat 2 minutes longer. Cool slightly. Stir in sour cream until well blended. Transfer to a bowl, cover and chill.
Fill tart shells up to 1 hour before serving. Garnish with whipped topping and gumdrops cut into flower shapes with lemon rind centers. Refrigerate leftovers.
"I must say this is the best recipe software I have ever owned."
"Your DVO cookbook software saves me time and money!"
"I saw lots of recipe software for PC computers but I was having a hard time finding really good mac recipe software. I'm so glad I discovered Cook'n! It's so nice to have all my recipes in a computer recipe organizer. Cook'n has saved me so much time with meal planning and the recipe nutrition calculator is amazing!!!
My favorite is the Cook'n Recipe App.