In a large stock pot, put on enough water to cook the pasta. Add a tablespoon of salt to the water.
Place a heavy frying pan, preferably cast iron, over medium-high heat. Add the neutral oil and beef. Add salt and pepper to the beef (be gentle with the salt). Brown the meat on all four sides, this will take roughly 6-8 minutes. We’re looking for a nice medium temp on the steak, so be careful not to overcook it. Remove and set aside on a cooling rack.
In the same pan, add 2 tablespoons of the butter along with the shallots, carrots and garlic. Cook until soft, about 5-8 minutes. Then add in the flour, mixing to fully incorporate, then cook for 2-3 minutes. Then add the beef stock, soy sauce and mustard. Bring to a simmer then reduce the heat to medium.
While the sauce is reducing and the pasta water is boiling, cook the pasta according to the directions on the package for “al dente.” Strain, add remaining butter and stir.
Once the sauce is thick enough to coat the back of a spoon, add the beef back into the sauce with half of the parsley and simmer for 3-5 minutes. Dump the pasta into a large pasta bowl or serving platter and then pour the meat and sauce over top. Sprinkle with remaining parsley and serve.