Cut Boston butt roast into cubes, season with salt and pepper.
Heat olive oil in a skillet, brown pork on all sides (optional but recommended).
Place carrots, potatoes, onion, celery, and garlic into the crockpot.
Add browned pork on top of vegetables.
Stir in broth, tomato sauce, tomato paste, Worcestershire sauce, thyme, rosemary, and bay leaves.
Cover and cook on low for 8–9 hours or high for 4–5 hours, until pork is fork-tender.
In the last 20 minutes, stir in frozen peas. Remove bay leaves.
Garnish with parsley and serve warm with bread, rice, or noodles.