There are a lot of ways to make stroganoff, from filet with real sour cream to chuck with mushroom soup. I usually don't make it for large groups, as it does not hold particularly well and is very easy to overcook. Plus, the noodles can get pretty gummy being help separate from the sauce.
For example, here is a typical food service recipe for stroganoff for about 85:
16 lbs beef round steak, boneless, 3/4 inch thick
1 cup vegetable oil
8 lbs mushrooms, sliced
3 lbs, 10 oz onions, chopped
(6) 50 oz cans Campbell's Cream of Mushroom Soup
1 qt water
3 qts sour cream, fat free
1/4 cup paprika
12 lbs, 8 oz Signature Egg noodles, medium
Slice beef into very thin strips. In large saucepot in hot oil, cook beef, mushrooms and onions until beef is browned. Drain fat. Add soup, water, sour cream and paprika. Heat through, stirring occasionally.
Cook noodles according to package directions. Rinse and drain. Portion meat mixture using 6 oz ladle (3/4 cup) over 1 cup cooked noodles.
Yield: 100 servings (3/4 cup beef mixture and 1 cup noodles each).
But I would not use this for a fancy dinnner or catering. Please send more information about your event.