Pre-heat oven to 450°F. Prepare tenderloin in baking pan with rack. Bring to room temperature for at least 20 minutes.
Coat beef with olive oil on all sides. Mix salt, granulated garlic and black pepper in small bowl and then liberally coat the tenderloin. Place in over and roast uncovered until internal temperature reaches 130°F.
Remove from oven and lightly cover with foil. Let rest for approximately 15 minutes.
Carve into ¼” slices and serve on a platter with French onions and horseradish sauce on the side.
Coat large, heavy bottom pot or cast iron with oil over medium heat, add butter and let melt.
Stir in onions, seasoning liberally with salt and pepper. Stir frequently until onions begin to soften. Add thyme, rosemary and bay leaf and let onions cook slowly until caramelized, stirring occasionally. Once onions are caramelized, remove herb sprigs and bay leaf and add rice wine. Let simmer for another 15 mins or so. Keep warm until ready to serve.
Combine mayo, sour cream, horseradish, lemon zest and lemon juice in small bowl. Whisk until combined. Season with salt and pepper to taste, then refrigerate until ready to serve.
