Inspect and wash beans. Put beans in a pot, cover with 3 times their volume of water.

Bring to a boil, boil for two minutes. Remove from heat, cover, and let stand for one hour. Drain beans and discard the soaking liquid. Put the beans in a large pot, cover them with the water, and add the bay leaf and 2 whole garlic cloves. Cover the pot and simmer the beans very slowly until they are tender, aout 2 hours. While the beans are simmering, prepare the sauce. Heat the oil in a skillet, add the onions, and saute until they start to brown. Add the 4 minced garlic cloves and the bell pepper, lower the heat, and continue to cook until the vegetables are sizzling. Stir in the vinegar and thyme. Spoon out about 1-1/2 cups of beans and liquid from the pot into the skillet of onions and garlic.

Gently mash the mixture with a potato masher. Stir the mashed bean mixture back into the bean pot. Adjust the seasoning with salt and pepper. Spoon the beans over steamed rice,or mix them into the rice, and serve as a side dish.