InstructionsStep 1: Slice the roast into large bite-sized pieces, trimming the excess fat as you go.Step 2: Place the meat in a large metal roaster with a little oil. Season with half tsp pepper and cook over medium-high heat for about 10 minutes until all sides are lightly brown. You can also do this in a large frying pan.Step 3: Add the broth to the roaster/pan once the beef is lightly browned on all sides along with the onion, soup mix, A-1, garlic, horseradish, mustard, half teaspoon kosher salt, and 1 1/2 teaspoons pepper. Dot with butter, then bring to a boil. Put the lid on, then adjust the heat to low and simmer for about 1 1/2 hours, stirring 2 to 3 times as it cooks.Step 4: After 1 1/2 hours, add the mushrooms and continue to simmer for another 15 to 20 minutes, covered.Step 5: Take the lid off and slowly stir in the cornstarch mixture (dissolved in cold water). Simmer further, stirring often until the sauce has slightly thickened. Cover again and keep it aside.Step 6: Following the package directions, cook the noodles in a large pot with salted boiling water. When done, drain and add to the beef. Stir well.Step 7: Serve right away with warm crusty bread and butter with vegetables on the side like green beans or a nice garden salad. Enjoy!