Heat the bacon in a large pot over medium high heat until lightly browned but still tender. Add the onion and saute until tender, 6 to 8 minutes. Add the garlic and saute a few more minutes.
Add the green beans and enough broth to cover, bring to a boil, reduce heat to low, and simmer, covered, for 25 to 35 minutes, until the beans are very tender. Season with salt and pepper to taste. Add hot pepper vinegar if desired.