1 stick butter (do not use unsalted butter)
1 pound tender cut of beef (tenderloin or tri-tip)
2 cloves garlic if desired
8 to 10 ounces white button mushrooms, washed
1 large white onion OR 2 medium shallots, (or similar weight in boiler onions)
1 1/2 cup beef broth (strong, if avaliable)
1 cup sour cream (may substitute 1 cup heavy whipping cream)
Approx. 1/2 cup all-purpose or whole wheat flour
1 Tbsp dijon mustard or 2 Tsp mustard powder
Salt, pepper, paprika to taste
Optional: 1/2 cup white wine
Optional: 1/4 cup balsamic vinegar
Peel onions or shallots. If using boiler onions, chop larger onions in half. Otherwise, dice onions coarsely. Peel and mince garlic. Chop mushrooms; I like to chop them in quarters.
Clean beef and slice into strips; the thinner the strips, the quicker they cook. I use strips between 1/3 and 1/2 inch thick. In large skillet, melt approx. 1/4 stick of butter; brown beef on high heat. Set browned beef aside and keep warm.
Add remaining butter (no, this isn’t a healthy dish, particularly) to leavings from browning beef and melt. Into melted butter, add garlic and onions. On medium-high heat, sautee until onions begin to turn transparent; add mushrooms and sautee until mushrooms darken.
Add vinegar, if desired, and cook uncovered until nearly dry.
Add wine, if desired, and cook uncovered until liquid is reduced by half.
Add 1/4 cup beef broth, cover, and reduce heat to simmer. Cook for five to ten minutes, or until onions are mostly limp.
Uncover. Add mustard and stir. Add the flour slowly, stirring well, until all flour is absorbed. The liquid remaining in the mixture should be the texture of thick gravy; if not, use additional flour a small spoonful at a time.
Return heat to high. Add remaining beef broth and browned beef. Bring to a brisk simmer; season with salt, pepper, and paprika to taste. I recommend:
1 tsp pepper
1/2 tsp salt
1 1/2 tsp paprika
but your tastes may vary.
Cover and cook until beef is desired doneness; ten to twenty minutes depending on altitude and thickness of beef.
Uncover, reduce heat to just below a simmer. Add sour cream or whipping cream, stirring carefully. Do not allow mixture to come to a simmer. Once cream has been added and brought up to temperature, remove from heat.
Serve over noodles or rice. This is a rather heavy dish, so light vegetables go well with it, as does a nice light salad.