Preheat oven to 400 degrees F.
In a food processor, combine pecans and cornbread and process until pecans are finely chopped. Melt butter in medium-size skillet over moderate heat. Add the garlic and cook until fragrant—about 1 minute. Stir in the pecan mixture to blend with butter and garlic. Set aside to cool slightly.
Pat pork dry and sprinkle with salt and pepper. Place in an oiled shallow baking pan. Spread mustard thickly over tenderloins and pat crumb mixture onto mustard. Roast in middle of oven 15 minutes. Tent pork loosely with foil to prevent crust from burning and continue to roast until thermometer inserted diagonally into center of meat registers 158 degrees F—about 15 minutes longer. Let meat stand 10 minutes before slicing.
Nutrition information per serving: Calories: 396; Protein: 44g; Carbohydrate: 6g; Fiber: 1g; Total Fat: 21g; Saturated Fat: 6g; Cholesterol: 130mg; Sodium: 242mg.