Sauté the diced onion in the oil for about 5 minutes, or until softened. If you are making this recipe on the stove, then add the remaining ingredients to a 3 to 4-quart pot, cover and simmer for about 45 minutes. If you are using a crockpot, then add the sautéed onions to the pot and then add the remaining ingredients, cover, and cook on low for 8 hours or high for 4 to 5 hours. To test and see if the beans are cooked you can take a few out and mash them between your fingers. They should be soft and mash easily. If not, continue to cook until done. Serve hot.