Cut the beef into thin strips, 1/8 inch thin. Make sure to cut against the grain, not with the grain, so that the meat won’t be chewy. Season the beef with steak seasoning, or salt and pepper.
Sear on high heat in batches. Cook only until brown on one side. Set aside.
In the same skillet, melt the butter, add onion and mushrooms, season with salt and pepper and cook until tender and golden. Add garlic and cook until fragrant, about 30 sec.
Add flour. Cook for 1-2 min, until all the flour is incorporated into the onions and mushrooms.
Deglaze with white wine and chicken broth. When you sear the meat, it will create brown bits on the bottom of the pan.This is called fond – caramelized bits of food on the bottom of a pan. It will give the sauce an amazing flavor. Use the whisk to scrape off all the fond when you pour in the liquid.
If you are cooking a large amount of meat, needing to sear it in many batches and are afraid the the fond will start to burn, pour in about 1/4 – 1/3 cup of water or broth, scraping up all the fond with a whisk and pour the liquid out into a vessel, set aside and continue searing. Pour the liquid back in when you are deglazing the pan and making the gravy.
Cook on med-high heat for 15-20 minutes. The sauce will thicken and reduce.
If it’s thicker than you like, add a little more broth.
Take off heat. Add sour cream, heavy cream, beef. Season with salt and pepper. I season last because as the sauce reduces, the flavors concentrate and the saltiness will become more pronounced.
Beef Stroganoff is a quick weeknight dinner option but is also great to prepare ahead of time. All it needs is to be reheated and served. If the sauce is too thick, add some more broth. I like making this for parties or making an extra batch to have leftovers for the next day.