Heat a large pot on medium-high, add oil and saute the onions and bacon until the onions start to brown and the fat has fully rendered from the bacon. About 8-10 minutes. Deglaze the pot with 1/4 cup of chicken stock, scraping up the cooked on bits with a straight-edged wooden spoon.
Add the greens in fistfulls and saute until it has all begun to wilt. Stir in the broth along with the balance of the ingredients, excluding the vinegar. Reduce heat, cover, and simmer until the greens are very tender. About 1 and 1/2 hours.
Stir in the vinegar and adjust the salt and pepper. Serve.