1. Prepare APRICOT FILLING: Combine apricots and water in a 1-quart saucepan over medium-high heat. Bring to boil; reduce heat, cover and simmer 5 minutes. Drain. Place apricots and corn syrup in blender or food processor. Cover and blend 2 minutes on high speed or until smooth. Cool completely. Makes 1-1/2 cups filling.
2. Prepare PASTRY: Combine flour, sugar and salt in a large bowl. Cut in butter using pastry blender or two knives until mixture resembles coarse crumbs. Stir in egg yolks and sour cream. Turn onto floured surface; knead just until smooth. Divide dough into four equal pieces. Cover; refrigerate for 1 to 2 hours until dough is firm.
3. Preheat oven to 375°F. Moisten work surface slightly with water; cover with plastic wrap. Working with one piece of dough at a time, roll dough between pieces of well-floured plastic wrap into a 10-inch square. (Keep remaining dough refrigerated.) Cut dough into 2-inch squares.
4. Spoon 1/2 teaspoon Apricot Filling diagonally across middle of each square. Fold two opposite corners of square over filling, overlapping slightly. (If necessary, moisten corners with water before folding.) Place on ungreased baking sheets.
5. Bake 10 to 13 minutes until edges are lightly browned. Cool on wire racks.
6. Store in tightly covered container. Sprinkle with powdered sugar before serving.

NOTE: For larger pastries, cut into 2-1/2-inch squares. Fill each square with a heaping 1/2-teaspoon Apricot Filling. Bake as directed for 12 to 15 minutes. Makes about 5 dozen pastries.

TIPS: Dough needs to be firm or it will be too sticky when rolled. To speed chilling of dough, place in freezer for 30 to 60 minutes.Dough may also be rolled on a floured pastry cloth with a stockinette-covered rolling pin (instead of between pieces of floured plastic wrap).