Cook egg noodles according to package directions while preparing sauce.
In a large skillet, heat the oil until hot over medium heat, then add the meat to skillet. Season with salt and pepper and cook over med heat, stirring occasionally, until lightly browned in spots but still rare, 3-4 minutes. Transfer meat to a platter, tent with foil, and set aside.
In the same skillet, melt 2 tablespoons of the butter. Add the onion to the skillet, season with salt and pepper, and cook over medium heat until the onions begin to brown at the edges, 5-8 minutes.
Once the onions are translucent and beginning to brown, add the mushrooms and garlic to the skillet with the remaining 2 tablespoons of butter. Season with salt and pepper and cook over medium heat until the mushrooms are tender and the garlic is fragrant, about 5 minutes.
Slide the skillet off the heat and add the Cognac to the mushrooms and onions; stir-in as it evaporates. Return the skillet to medium heat and add the tomato paste and stock; bring to a rapid simmer and cook to reduce for 5 minutes.
Stir in the creme fraîche and gently simmer until thickened, about 5 minutes. Taste the sauce and season with additional salt and pepper, as desired.
Add the meat, including any accumulated juices, to the mushroom sauce and simmer just until heated through, about 2 minutes. Serve over egg noodles and garnished with parsley and Parmesan cheese.
The cut of meat is important here because the cooking time is brief, these cuts work best: beef tenderloin, tri-tip steak, Teres major a.k.a. petite tender or shoulder tender, skirt steak, bavette or flap meat as indicated in recipe. When using skirt steak or flap meat, be sure the strips are cut across the grain for tenderness.