-
1
Pour boiling water over porcini in a small bowl and soak until softened,10 to 20 minutes.
-
2
Lift porcini out of water, squeezing excess liquid back into bowl, and rinse well to remove any grit.
-
3
Pour soaking liquid through a paper-towel-lined sieve into a bowl and reserve.
-
4
Finely chop onion and garlic in a food processor, then add cremini and porcini and pulse until very finely chopped.
-
5
Heat butter in a skillet over moderate heat until foam subsides, then cook mushroom mixture, stirring frequently, until mushrooms are dry and 1 shade darker, about 8 minutes.
-
6
Add reserved soaking liquid and simmer, stirring frequently, until mixture is thick, dry, and beginning to brown, about 15 minutes (there will be about 1 cup filling).
-
7
Stir in parsley and salt and pepper to taste.
-
8
Cool completely.
-
9
Halve dough and roll out 1 piece on a lightly floured surface into a 15-inch round, keeping remaining dough wrapped.
-
10
Cut out rounds (about 24) with floured cutter.
-
11
Put 1 teaspoon filling in center of each round.
-
12
Working with 1 round at a time, moisten edges with water and fold in half to form a half-moon, pinching edges together to seal.
-
13
Transfer pierogies as assembled to a flour-dusted kitchen towel.
-
14
Repeat with remaining rounds, then make more pierogies with remaining dough and filling.
-
15
Cook onions in butter in a large heavy skillet over moderately low heat, stirring frequently, until golden brown, about 30 minutes.
-
16
Season with salt and pepper and keep warm.
-
17
Cook pierogies in a large pot of lightly salted boiling water until tender, 12 to 15 minutes.
-
18
Transfer with a slotted spoon to skillet with onions.
-
19
Toss gently to coat and serve immediately.
