Crockpot Beef Stroganoff

Made this last year for Jeff's birthday. We were blown away by how good it was... and have yet to make it again, but I just might make this again soon! So fun to be able to make it in the crockpot, also... thanks, Martha Stewart!

2 pounds beef chuck, trimmed of excess fat and cut into thin slices (about 1/2 inch thick and 3 inches long)

1 large onion, chopped (about 2 cups)

***1 pound white mushrooms, trimmed and halved (or quartered, if large)

Coarse salt and ground pepper

2 tablespoons cornstarch

1/2 cup reduced-fat sour cream

2 tablespoons Dijon mustard

Cooked thin egg noodles, for serving

Chopped fresh dill, for garnish (optional)

***Now you know Jeff hates mushrooms, so I omitted these – if you choose to do the same, add more liquid at the beginning! (i.e. some beef broth, I used chicken broth and it tasted great, or just water) It will get a bit too dry during the cooking process, and at the end you need some liquid to make the sauce come together. You can improvise like I said with beef broth if it comes out dry. Don’t worry!

In a 5- to 6-quart slow cooker, toss beef, onion, and mushrooms with 1 1/2 teaspoons coarse salt and teaspoon pepper. Cover, and cook on low until meat is tender, about 8 hours (or on high for 6 hours)

In a 2-cup glass measuring cup, whisk cornstarch with 2 tablespoons water. Ladle 1 cup cooking liquid into measuring cup; whisk to combine. Pour into a small saucepan, and bring to a boil; cook until thickened, about 1 minute. With slow cooker turned off, stir in cornstarch mixture, then sour cream and mustard. Serve beef over noodles; sprinkle with dill, if desired.