Pierogies (Outstanding) - cooking recipe

Ingredients

3 cups all-purpose flour
1 cup regular sour cream
2 large whole eggs
1/2 teaspoon salt
8 medium russet potatoes
8 ounces extra-sharp cheddar cheese, shredded

Preparation

Filling:.
Shred the cheese and set aside.
Peel, cube and cook until tender the 8 potatoes. Drain.
Place half the potatoes in a mixing bowl (I utilize the KitchenAid) add the shredded cheese and top with the remaining potatoes. Beat well, tasting if the seasoning seems correct for your taste. Let cool.
The filling may be made the day before. Let cool completely before covering otherwise it may sweat and make the potatoes a little watery.
Dough:.
In a food processor bowl place all the ingredients starting first with the flour. Let process until all the dough comes into a ball and the sides of the processor are clean. Shape into a flat disc using flour is a little sticky. Wrap in plastic wrap and let rest 30 minutes.
Flour your working area and roll the dough fairly thin. Just to give you an idea, you should get approximately 38 to 40 pierogies out of this recipe.
Cut the dough into a circle using a top from a wide mouth canning jar or anything which is about that size. Wet the one side of each circle and place a walnut sized portion of potato mixture onto the center. Fold over and pinch well. Set each pierogie on a parchment lined cookie sheet separated from each other.
Continue to use up all the dough.
Bring a 5 quart pot to a boil. Using a wooden spoon keep stirring the water as you place each pierogi in to cook. Cook only about 10 at a time. Let them surface and continue to cook for about 2 minutes.
Have a large bowl of cold water on hand. Remove the pierogies and place them in the cold water for several minutes. Drain each one well so no water remains on them and roll them in some vegetable or canola oil shaking off the excess oil. This is needed so that they won't stick together.
You may use quart sized ziploc bags to bag about 10. Lay them place on a cookie sheet and at this point they may be frozen until ready for use.
When preparing about 10 or 12:.I wouldn't put any more in one fry pan.
Using a large coated fry pan, melt 1/2 to 1 stick butter or margarine. Add 1 cup diced onions and saute until soft and golden but not brown. Add about 3 tablespoons of water and lay your unfrozen pierogies on top. Cover with lid and on low flame allow them to become soft and puffy. Be careful not to cook any faster because the bottoms will get browned.
When ready to serve pour onto a dinner sized plate. It's easier to scoop out than from a bowl.
Really, these are just the best and I've tried many recipes.