Use fresh green beans, but don’t overcook them or they will lose their bright green color.
Fry bacon in soup kettle until crisp. Remove, drain, and set aside. Saute onions and garlic in remaining fat until soft. Add stock, bay leaf, vinegar, and potatoes; bring to a boil, reduce heat, and simmer, partially covered, 15 minutes. Add beans and simmer 10 minutes longer or until beans are tender. Season with salt and pepper. Remove bay leaf. Garnish with reserved bacon, crumbled.