Beef tenderloin roasted with shiitake mushrooms and thyme is impressive. Creamy shallot-brandy sauce is for spooning over the beef; sprigs of thyme tucked underneath hint at one of the flavors.
Preheat oven to 425 degrees. Season beef with salt and pepper. Heat 2 tablespoons oil in a large skillet over medium-high heat. Add beef, and brown on all sides.
Toss mushrooms with remaining 2 tablespoons oil in a bowl; season with salt and pepper. Add mushrooms and 3 thyme sprigs to skillet; place in oven. Cook until beef registers 125 degrees for medium-rare, 18 to 20 minutes. Let stand 20 minutes. Serve warm or at room temperature with mushrooms and shallot-brandy sauce. Garnish with thyme.