Zest lemons to measure 1 tablespoon lemon peel. Juice lemons, lime and orange; pour into measuring cup to measure 1 cup. Mix sugar, lemon peel and juices in a medium heavy saucepan.
Stir in butter and egg yolks. Cook and stir over medium-low heat for about 8 minutes until mixture thickens and coats back of a spoon and reaches a temperature of 180°F (do not boil).
Pour into clean bowl or 1 cup glass containers. Cover and store in refrigerator for up to 1 week.
When ready to assemble, bake phyllo tarts according to package instructions and allow to cool.
Fill phyllo tarts with chilled lemon citrus curd. Garnish with blueberries and whipped cream and a sprig of mint, if desired.
Serve remaining curd with scones, muffins, or toast.
