In a small bowl, combine butter, minced garlic, rosemary, thyme, smoked paprika, sage, Dijon mustard, lemon zest, salt, and pepper. Rub this mixture all over the pork tenderloin, making sure to cover the top, sides, and bottom thoroughly.
3 tablespoons salted butter, 4 garlic cloves, 1 tablespoon fresh rosemary, 1 teaspoon thyme leaves, 1 teaspoon smoked paprika, 1 teaspoon ground sage, 1 tablespoon Dijon mustard, 1 teaspoon salt, ½ teaspoon fresh ground black pepper, 1 teaspoon lemon zest