On the night before cooking, optionally soak the beans in water. Soaking slightly reduces the cooking time, as well as helping to remove the sugars which can cause bloating, discomfort, and flatulence.
Preheat oven to 170c/gas mark 3.
In a large casserole dish, add the beans and cover with water until 2-3 cm above the beans and season with salt. Cover with a lid and bake for around 1.5 hours until tender, topping up with water as needed. Timings can vary.
Drain the beans retaining the cooking liquid. Dry your dish, and on a medium heat add a splash of oil and the bacon or diced pork belly, and cook until browned and crispy.
Remove the bacon or pork belly and using the leftover fat, sauté the onions for a few minutes until softened. Add the garlic and tomato purée and sauté for one more minute. While waiting for the onion and garlic to sauté, dice the bacon if used instead of pork belly.
Add all other ingredients to the dish (including the bacon but excluding the beans) and season with salt and pepper. Be generous with the pepper. Return the drained beans to the dish and add just enough of the beans’ cooking liquid to cover the beans (reserve the rest for the next step). Mix thoroughly.
Bring the mixture to the boil on the hob and transfer to the oven with a lid on. Bake for 4 hours, topping up with the beans’ cooking juice (or water) as needed. For the first half of the cooking time, keep covered, then remove the lid for the rest of the cooking time. During the last hour of cooking, avoid stirring as this will allow a ‘crust’ to form on the surface. Discard the bay leaves when serving.