In 1-quart pot over medium heat, brown shallots and mushrooms in small amount of olive oil.
Add whole garlic clove, thyme and broth. Simmer for 10 minutes.
Remove garlic clove.
Mix together cornstarch and water to form a slurry.
Bring sauce to a boil and whisk in slurry.
Cook 1 minute, then remove from heat.
Preheat oven to 425° F.
Remove meat from refrigerator to sit at room temperature for 30 minutes. Brush with olive oil and season with salt and pepper.
Place roast in roasting pan and put in oven. After 15 minutes, turn temperature down to 300° F. Roast will take approximately 2 hours to reach medium-rare doneness of 135° F internal temperature.
Once roast is cooked, add pan juices to sauce and allow roast to rest 10 to 15 minutes before slicing across grain. Serve with Mushroom Sauce.