Heat 2 tbsp of olive oil in a large skillet over medium-high heat.
Add the thinly sliced ribeye steak.
Season with salt and pepper, and cook until browned on all sides.
Remove the steak and set it aside.
In the same skillet, melt 2 tbsp of butter.
Add the chopped onions and minced garlic, sautéing until the onions become translucent and fragrant.
Add both the button and shiitake mushrooms to the skillet.
Cook until they are tender and have released their moisture.
Pour in the dry white wine, allowing it to simmer for a few minutes.
This helps deglaze the pan and builds flavor.
Incorporate the beef broth and bring the mixture to a gentle boil.
Stir in the sour cream and flour, ensuring the flour is fully dissolved.
Reduce the heat to low and let it thicken slightly.
Add the cooked beef back into the skillet, coating it with the sauce.
Simmer for an additional 5 minutes.
Serve the stroganoff garnished with fresh thyme.