Reduce heat to medium and add onions and garlic, sautéing 2-3 minutes until soft. Add port and stir to scrape up all the browned bits from the bottom of the pan. Bring to a simmer and reduce liquid for 5 minutes. Add broth, tomatoes, Worcestershire sauce, tomato paste, rosemary and bay leaf. Stir to combine and bring to a simmer. Cover and braise in oven for approximately 2 hours or until meat is tender.