Put all of the ingredients into your slow cooker . Stir them well Set slow cooker to your desired heat setting depending on how long you want it to cook for, I cooked mine on low for about 7 hours as I was at work all day but if you set it to high it would be ready after about 4 hours. If you don't have a slow cooker you can also cook this in a pan or in the oven. Start by sautéing the onions and garlic then add all of the other ingredients. I don't use any oil and just use a dry pan but if you want to use a little oil that's fine too. Simmer for as long as you can to get the best flavour but at least until the beans are tender, 3 hours at least, less if you are using pre-cooked or canned beans. If using canned it could be ready in as little as 40 minutes. The longer it simmers the better it will be though! If cooking in the oven set oven to 300°F and cook until the beans are tender and the sauce rich and thick. Check your beans are cooked through and soft before serving.