This recipe says "In a large soup kettle, combine the beans, water, salt and baking soda. Bring to a boil, cover, and simmer for 5 minutes. Remove from the heat, skim off foam, re-cover, and let stand for 2 hour. (The beans can also be soaked overnight if you prefer.)" I assume you are using dried beans in this recipe because of the soaking time. If you salt those beans before they are cooked completely, they will never cook to the soft stage. Same goes if you add tomatoes to dry beans before they are cooked completely. Just thought I would solve a problem others may have had and not been able to figure out.