Heat the canola oil in a large oven-safe skillet or dutch oven. Add the flour and cook, stirring, until thick and golden. Add the onions and cook until soft, about 5 minutes. Add the sherry vinegar, beef stock, salt and pepper. Bring to a boil, reduce the heat to a simmer and cook for 10 minutes. Stir in the cremini mushrooms and return to a boil.
Meanwhile, heat a large skillet over medium heat with a drizzle of oil. When hot, add the beef, being careful not to crowd the pan, and sear on all sides, turning when one side is browned. Remove the meat to a plate.
Add the seared meat and any accumulated juices to the braising liquid in the dutch oven. Cover with a piece of parchment paper pushed down so it's touching the surface of the meat, then a secure lid. Braise for 90 minutes, or until the beef is falling-apart tender. Remove the meat from the braising liquid and cover to keep warm. Return the braising liquid to the stove and bring to a simmer to reduce. When thickened and creamy, whisk in the sour cream until completely dissolved. Turn off the heat.
Towards the end of cooking time, bring a large pot of salted water to a boil for the pasta. Add the egg noodles, stirring to prevent clumps. Cook to al dente, according to package instructions, strain and return to the pot and toss with a pat of butter to prevent sticking.
Warm the peas in a microwave-safe bowl or small saucepan with a few tablespoons of water until hot. Season with salt and pepper to taste.
In a small bowl, combine the butter and half of the chopped parsley to make parsley butter.
To serve, divide the butter noodles between plates. Top with beef, sauce, peas, parsley butter and fresh parsley.