1 In a mixing bowl, cream the shortening, butter, and sugar together. Add the eggs and blend until smooth. (If the mixture is hard to blend or seems curdled, add a bit of the flour to bind it.)2 Stir in the orange juice or milk and the vanilla. Fold in the flour, salt, and baking powder and mix to make a firm but soft dough. Transfer the dough to a lightly floured work surface and pat the dough into a smooth mass. Cover and let it rest for 10 minutes.3 Preheat the oven to 350°F. Line 2 large baking sheets with parchment paper.4 Divide the dough into 2 or 3 flattened discs and work with one portion at a time.5 Roll out the dough on a lightly floured board to a thickness of 1/8 inch. Use a 3-inch cookie cutter and cut as many rounds as you can. Brush the rounds with egg wash. Fill with a generous teaspoonful of the desired filling. Draw 3 sides together into the center.6 You should now have a 3-cornered or triangular pastry. Repeat this process with the remaining dough and filling. Brush the pastries with additional egg wash. If desired, sprinkle with regular or coarse sugar, and bake in the center of the preheated oven until golden brown (18 to 25 minutes). Cool on the baking sheets.7 If you prefer, this dough can be made ahead and refrigerated, wrapped in plastic, for up to 2 days, or frozen (either as a disc of dough or as already formed and filled pastries, for a couple of months). If refrigerating, allow the dough to warm up before rolling out. For frozen pastries, bake without defrosting.