Heat Dutch Oven over medium-high heat.
Add oil; swirl to coat.
Sprinkle pork with 1/4 teaspoon salt and 1/4 teaspoon pepper.
Add pork to pan; cook 10 minutes, turning to brown all sides.
Remove Pork to a bowl.
Add onion, bell pepper, and garlic to Dutch Oven and sauté for 5 minutes or until tender.
Add Pork back in to Dutch Oven .
Add remaining 1/4 teaspoon salt, 1/4 teaspoon pepper, tomatoes, rosemary, and thyme.
Cover with lid and cook @ 94'C (200'F) for 7 1/2 hours.
Add vinegar and Worcestershire sauce.
Cook, uncovered, for 30 minutes; turn off heat.
Shred pork with 2 forks.
Combine 2 cups water and milk in a saucepan over medium heat; bring to a boil.
Reduce heat to low; add polenta, stirring with a whisk.
Cook for 4 minutes, stirring frequently.
Remove from heat; stir in cheese and remaining 1/4 teaspoon pepper.
Serve pork over polenta in shallow bowls.