Potato Pierogi - cooking recipe

Ingredients

2 c. all-purpose flour
2 eggs
1 tsp. salt, divided
1/3 c. water
5 Tbsp. butter or margarine, divided
1/2 c. chopped onion
1/4 tsp. white pepper
2 c. cold mashed potatoes
sour cream (optional)

Preparation

Combine flour, eggs, 1/2 teaspoon salt and water in a mixing bowl.
Mix well to make a medium soft dough.
Knead well until dough is firm.
Cover with a warm towel and let rest 10 minutes.