Soak the beans overnight in cold water. Rinse thoroughly, picking out any of the skins.
Peel the onions, tomato, potato, and garlic, leaving whole. Cut the onions, tomato, and potato in half.
Place the beans in a large pot, add the vegetables, tea pocket, bouquet garni, bay leaves, and cover by an inch or two with stock.
Simmer 1-2 hours, stirring occasionally, adding more water if necessary.
When the beans are soft, remove the onion, chopping and mashing up. Mash the tomato, potato and any garlic pieces.
Remove the bouquet garni, the tea pocket and bay leaves.
Add more water if desired, add the olive oil and the vinegar, stir to combine.
Salt and pepper to taste.
Serve with buttery sourdough toast.