Beef Stroganoff with Cremini & Porcini Mushrooms

1/2 oz. dried porcini mushrooms (about 1/2 cup)

3 Tbs. vegetable oil (not olive oil)

1/4 cup unsalted butter

8 to 10 oz. fresh cremini mushrooms, stems trimmed, caps wiped clean and thickly sliced

1 lb. beef tenderloin, cut into strips about 2 inches long and 1/2 inch wide

Kosher salt and freshly ground black pepper

3 Tbs. all-purpose flour

1 medium onion, thinly sliced

1 Tbs. Dijon mustard

1/2 tsp. Worcestershire sauce

5 Tbs. creme fraiche

For serving:

Cooked egg noodles or fresh egg fettuccine

2 Tbs. chopped fresh flat-leaf parsley