Beef Stroganoff

beef stroganoff might be considered  somewhat old fashioned but I love it. perhaps its so 70's but its still so good! recipe mostly from The Australian Womans Weekly Cookbook 1970 edition except I add a little tomato paste to the recipe.

2 lb rump or fillet steak
1/2 lb mushrooms
1/2 cup sour cream
1 teaspoon salt
pepper
1 onion
1 oz butter
cut meat into strips approx 1/2 inch by 2 inch. melt butter in pan & fry chopped onion, add meat and continue to cook untill almost done. add sliced mushrooms, fry until meat is tender. pour in sour cream, season to taste & heat through gently.