Melt 3 tbsp of butter in a large frying pan on low/ medium heat. Increase the heat to high/medium and add strips of beef. Cook the beef quickly, browning on each side, so the temperature needs to be high enough to brown the beef, but not so high to burn the butter. While cooking the beef, sprinkle with salt and pepper. When both sides are browned, set aside in a bowl.

In the same pan, reduce the heat to medium and add shallots. Cook the shallots for a minute or two, allowing them to soak up any meat drippings. Remove the shallots to the same bowl as the meat and set aside.

In the same pan, melt another 3 Tbsp of butter. Increase heat to medium high and add the mushrooms. Cook, stirring occasional for 4 minutes. Sprinkle the nutmeg and tarragon on the mushrooms.

Reduce the heat to low and add the sour cream to the mushrooms. You may want to add a tablespoon or two of water to thin the sauce or not. Mix in the sour cream thoroughly. Do not let it come to a boil or the sour cream will curdle. Stir in the beef and shallots. Add salt and pepper to taste.

Serve immediately over egg noodles, fettcine, potatoes or rice