Rinse the dried black beans well. Transfer them to the heavy-based pot you’ll cook them in, cover with water (about 5 cm over the beans) and leave overnight.
The next day, drain the beans and rinse with fresh water. Set aside.
In your pot, heat the olive oil, add the onion and sauté for a few minutes until softened.
Add the beans, garlic, cumin, bay leaves, and water. Bring to a boil, reduce heat to a simmer, cover and cook until the beans are nearly tender, about 1¼ to 1½ hours.
Add the salt and continue to cook for another 15 minutes or so, until tender (but not mushy).
Remove from heat, drain and remove the bay leaves and enjoy. Alternatively, divide the beans into 4 x roughly 250g portions to freeze - this is equivalent to a drained tin of black beans.