Ingredients
Pierogi Dough
3 cups (390 g) all-purpose flour, plus additional for kneading
1 large egg
2 teaspoons vegetable oil
1 teaspoon salt, plus more for the boiling water
1/2 to 3/4 cup (120 to 180 ml) warm water

Filling
2 medium potatoes (white, baking, or Yukon gold—whatever you prefer), peeled and cut into chunks
6 strips bacon
3 large onions, peeled—1 minced and 2 sliced
1 cup (130 g) frozen baby peas, defrosted
9 oz (255 g) ricotta cheese
Salt and freshly ground pepper
5 tablespoons unsalted butter, plus more as needed
1 to 2 cups/240 to 480 ml light sour cream (optional)