Beef Stroganoff

This was my grandma's recipe, and despite the fact that I'm not a big meat eater, I love it.  It was perfect for a comforting Sunday dinner on a crisp fall night, and makes 6-8 generous portions.  It's unlike a lot of other stroganoff recipes in that instead of being creamy and white sauce-based, it's tomato-based.  You can stir in 1/2 cup or so of sour cream at the end to make it creamier, but I like it as is.

2 1/2 pounds beef, cut in 1/2 inch cubes (I use top round, trimmed of fat)
1/4 cup flour
1/4 cup butter, divided
1 large onion, diced
1 can sliced mushrooms (opt.) or scant 1/4 cup beef broth
1 15-oz. can tomato sauce or 2/3 cup tomato juice
salt & pepper
1 1/2 pound cooked pasta or rice

In a brown paper bag, toss cubed beef with flour until lightly coated.  Melt all but 1 Tbs. of butter in large skillet.  Brown beef on both sides, but don't worry about cooking it through (about 5 minutes).  Remove beef from skillet.  Melt remaining butter in skillet, the saute onions until softened.  Add in can of sliced mushrooms and their juice (or beef broth), tomato sauce  (or tomato juice), and browned beef.  Bring to a boil over medium heat, then reduce heat to low.  Simmer on lowest heat for approximately 1 hour, until beef is tender.  Crockpot option:  empty skillet into crockpot with additional 1/4 cup liquid, and cook on low 6 hours or high 3 hours until meat is tender.

When meat is tender, serve over cooked pasta or rice (I like whole wheat egg noodles or penne).