To make 56 vareniki (serves 6-8):
Dough: 3 cups all-purpose flour
1 teaspoon salt
3 egg yolks
1/2 cup cold water
The dough can be made easily using a food processor or an electric mixer fitted with a dough hook. The dough can be kneaded by hand, but because it is so stiff it will take longer than with the mixer.
Food processor method: Combine the flour and salt in the work bowl fitted with the steel blade. Process for 2 seconds to mix. With the motor running, add the egg yolks and water and process until the dough masses into a ball on the spindle. Remove the dough to a lightly floured surface and knead by hand 4 or 5 times.
Electric mixer method: Combine all the ingredients in the bowl of the mixer with the dough hook in place. Mix for 1 minute at low speed, then raise the speed to moderate and beat for 2 minutes; the dough should be well blended, smooth, and elastic. However you knead the dough, form it into 2 balls, dust lightly with all-purpose flour, cover tightly with plastic wrap, and allow to rest for 30 minutes. The dough can be frozen after it has rested (but do not merely refrigerate). To defrost, leave at room temperature for 2-3 hours; then proceed with the recipe.