- Preheat oven to 180°C (350°F).
- In a bowl, mix the butter, mustard, onion and parsley. Generously brush mixture all over roast. Pepper to taste. Place roast on a rack, then place rack on a dripping pan.
- Cook in oven for 1 hour and 30 minutes to 1 hour and 40 minutes or until internal temperature reaches 63°C (145°F). Remove from oven. Cover with foil wrap and let stand for 10 minutes. In the meantime, heat butter in a non-stick skillet over medium-high heat. Add mushrooms and garlic. Sauté for about 5 minutes or until mushrooms are cooked. Add salt and pepper
- to taste. Stir and keep warm.
- In the same skillet, heat butter over medium heat. Add onion and sauté until translucent. Add port and reduce by half. Add beef stock and bring to a boil. Use a whisk to incorporate kneaded butter. Strain sauce once it becomes smooth.
- By the plate: Serve roast sliced and topped with port sauce. Garnish with mushrooms, blue cheese and parsley.
- Self-serve: Slice roast and place on a serving platter. Garnish with mushrooms, blue cheese and parsley. Place platter and a gravy boat filled with port sauce on table and let guests serve themselves.
- At the table: Place unsliced roast and all accompaniments (sauce, mushrooms and cheese) on table. Slice roast for guests, serving as you go.
Serve with sautéed baby potatoes and mesclun salad.