Step #1 mix cr?me fra?che, paprika, tomato paste, & demiglace in a medium-size saucepan & let simmer slowly for 20 mins, salt, Worcestershire sauce, mustard, pepper to taste, or until sauce is slightly reduced.
Step #2 remove this from heat & let this stand, covered, while completeing recipe.
Step #3 Trim stem ends off mushrooms & discard.
Step #4 Wipe mushrooms with a damp paper towel & slice thin.
Step #5 Melt 3 tbsps of butter in a medium sized skillet & saut? mushrooms until tender & golden, about 10 mins.
Step #6 Transfer to a bowl & reserve.
Step #7 Cut a small X in the root end of each pearl onion.
Step #8 Bring a large kettle of water to a boil & drop in the onions.
Step #9 Blanch for 10 mins, drain, & rinse under cold running water.
Step #10 Peel the onions.
Step #11 Heat another 2 tbsps of butter in the same skillet & saut? the onions, stirring and shaking the skillet often, until they are lightly browned, 3 to 4 mins.
Step #12 Transfer the onions to the bowl with the mushrooms.
Step #13 Cut the meat into thin slices on the diagonal.
Step #14 Heat remaining butter in the skillet & saut? the pieces of filet over high heat until just lightly browned.
Step #15 Transfer pieces to a plate as each batch is browned.
Step #16 Recipe can be prepared to this point several hrs before serving.
Step #17 To complete, set sauce over med-heat/flame & bring to a simmer.
Step #18 Add mushrooms, onions & any accumulated juices from the bowl, and simmer for 5 mins.
Step #19 Add slices of filet & any accumulated juices & let simmer until the meat is heated through, about 2 mins.
Step #20 Serve as soon as possible over buttered noodles.
Step #21 Garnish with sliced parsley.
Step #22 Garnish side with saut?ed cherry tomatoes & pour a good red wine.