Can I use ground turkey or chicken instead of beef?
Yes. Ground turkey or chicken will work, though they're leaner; add a tablespoon of butter or olive oil to the pan to prevent drying out.
Can I make this ahead?
Prepare the beef and mushroom mixture up to 2 days ahead; refrigerate separately from the noodles. Reheat gently, then stir in fresh sour cream just before serving to avoid curdling.
Why is my stroganoff sauce curdling?
Sour cream curdles at high heat. Remove the pan from heat before stirring in sour cream, and keep the temperature low once added.
Do I have to use egg noodles?
No. Serve over egg noodles, buttered egg pasta, rice, or mashed potatoes; stroganoff sauce pairs well with any starch.
What does the reserved pasta water do?
Pasta water's starch loosens a thick sauce. Add it 1 tablespoon at a time if your stroganoff is too dense or won't coat the noodles.