To prepare pork, combine first 9 ingredients in a large zip-top plastic bag; seal and marinate in refrigerator overnight or up to 2 days.
Preheat oven to 40
Remove pork from bag.
Place pork on a broiler pan coated with cooking spray.
Bake at 400 for 30 minutes or until a thermometer registers 15
Remove from oven; cover and let stand 10 minutes before slicing.
To prepare polenta, heat a medium saucepan over medium-high heat. Coat pan with cooking spray.
Add onion and 2 garlic cloves; saut 2 minutes.
Add wine; cook 5 minutes or until liquid almost evaporates.
Add 2 1/2 cups water; reduce heat, and simmer 5 minutes. Gradually add polenta, stirring constantly with a whisk. Cook over medium heat 15 minutes or until thick and creamy, stirring frequently and gradually adding remaining 2 1/2 cups water. Stir in butter, 1 teaspoon salt, and 1/4 teaspoon pepper.