I used to love when mom would make this for us growing up in the '70s. For a second generation, I've made it for my children and now they are making it for theirs. Good, solid recipes stand the test of time.
Cut beef into 3" strips (3" x 1/2"). Place 1/2 cup flour, salt and pepper in large plastic bag. Add beef. Toss to coat. Place in oiled crock pot.
Add onions, mushrooms and beef broth to crock pot. Stir to coat.
Cook on low for 8 hours.
Combine sour cream with 1/2 cup flour. Stir into crock pot. Heat a few minutes longer until creamy and hot. Serve over hot cooked rice or wide noodles. Top with a dollop of sour cream and fresh parsley (or fresh chives) if desired. Enjoy!