Step 1 In a 6-quart heavy-bottomed pot, combine the onion, carrots, celery, cabbage, garlic, oregano and vegetable broth. Bring to a boil over high heat, then reduce the heat, loosely cover and simmer until the vegetables are tender, 45 minutes to an hour.
Step 2 Stir in the split peas and bring back to a simmer. Cover loosely and continue to cook, stirring occasionally, until the peas have softened and started to break down, about 1 1/2 hours, thickening the soup. Add additional water if needed to thin the soup (we added 2 additional cups after 1 hour). This makes about 3 quarts of soup.
Step 3Season with the salt, white pepper and Worcestershire sauce, and let the soup simmer for a few more minutes to marry the flavors. Taste and season again as desired.