Soak the white beans overnight (12 hours)
Put terracotta (clay) cooking pot into the oven and pre-heat the oven to 170C (340F)
Rinse the beans well and put the rinsed white beans into a saucepan and add enough water to cover the top of the beans and boil for about 35 minutes until they are just starting to become tender. Drain and put it aside.
Put the butter, diced onions, sliced garlic cloves, long green peppers into a saucepan and cook until onions have a golden color. And then add the lamb cubes and saute until lamb cubes have brown color (about 5-8 minutes).
Add the peeled and chopped tomatoes, tomato paste, pepper paste, black pepper, salt and stir them well for about 5 minutes. Add the rinsed white beans and stir them all well. Make sure they all mix well and then close the heat and set the saucepan aside.
Take out the heated terracotta (clay) cooking pot from the oven and put the white beans with lamb mix inside the terracotta (clay) cooking pot and then add 6 cups of hot water into the clay pot and stir and then close the terracotta (clay) pot lid. Put the clay pot back in the oven and close the oven door. Cook 1 hour.