If you are using dried beans (you'll need around 350g) soak them in plenty of cold water and a teaspoon of baking soda overnight. Drain the beans and put them in a saucepan and cover with fresh cold water. Bring to a steady boil (don’t salt the water as this makes the beans tough), skimming off sediment as it rises to the surface. Cover and cook for 45mins - 1½ hrs until tender, then drain. The time will depend on how old your dried bean are.