Sheet Pan Beef Tenderloin with Mushrooms and Brussels Sprouts

Name: Sheet Pan Beef Tenderloin with Mushrooms and Brussels Sprouts
Ingredients: 2 cloves garlic; 2 tablespoons fresh parsley leaves, plus more for serving; 1 tablespoon fresh thyme leaves; 1 teaspoon fresh sage leaves; 3 tablespoons olive oil, divided; 1 tablespoon Dijon mustard; 2 teaspoons kosher salt, divided; 1/2 teaspoon freshly ground black pepper, divided; 1 (3-pound) center-cut beef tenderloin; 1 pound Brussels sprouts; 8 ounces cremini or white button mushrooms; 2 large shallots; 1 medium lemon; 2 tablespoons finely grated Parmesan cheese; 1/4 cup sour cream; 2 tablespoons mayonnaise; 1 tablespoon prepared horseradish