Slice steak across the grain into thin strips about 1⁄8-inch wide and 3-inches long. You’ll find it easier to thinly slice the meat if it is slightly frozen.

In a large nonstick frying pan, place the beef strips, mushrooms and onion.

Cook, stirring often, over medium-high heat, until the meat is well browned.

Add the broth, water, catsup and pepper.

Reduce heat, cover and simmer about 45 minutes, stirring occasionally.

In a small bowl, mix the flour with 1⁄4 cup of the buttermilk until smooth.

Add the remaining buttermilk; mix well.

Stir into the hot beef mixture.

Cook, stirring constantly, until thickened.

Serve immediately over the hot egg noodles.