Beef Stroganoff - cooking recipe

Ingredients

2 lb. beef steak (lean)
salt and pepper
2 Tbsp. butter
1 c. mushrooms
onion, thinly sliced
1 Tbsp. butter
2 Tbsp. flour
2 c. beef bouillon
3 Tbsp. sherry
2 Tbsp. tomato paste
1 tsp. dry mustard
2/3 c. sour cream
hot whipped potatoes

Preparation

Remove fat and gristle.
Cut into narrow strips 2 1/2-inches long, 3/4-inch wide and 1/4-inch thick.
Dust strips with salt and pepper.
Leave at room temperature at least 2 hours.