Prepare Beef
Slice flank steak.
Season beef with rosemary salt and pepper.
Combine flour, corn starch, onion powder, and garlic powder.
Toss beef in flour mixture to coat.
Remove excess flour from beef.
Cook beef in batches 2 minutes per side until golden brown.
Make Sauce
Cook mushrooms until browned.
Cook onion until golden brown.
Cook garlic and thyme for 2 minutes.
Deglaze with white wine until almost dry.
Return mushrooms to pan.
Add Worcestershire sauce.
Add beef stock and simmer until reduced by 80%.
Stir in Dijon mustard.
Whisk in heavy cream.
Whisk in cold butter cubes.
Add cooked beef and heat through 2-3 minutes.
Adjust seasoning.
Cook Noodles
Cook egg noodles according to package directions.
Serve
Serve stroganoff over egg noodles.
Garnish with sour cream and parsley.
