You can make it yourself from dry beans or use canned bean. If you want to cook from fresh, just follow the next few steps. Choose red kidney beans for the firm texture and shape, otherwise anything is fine.
Soak dry beans overnight
Drain the soaked beans, rinse and repeat.
Transfer beans to a pot with lid, add water to about 1 inch higher than the beans level
Bring to boil, then reduce heat and simmer for about 90 minutes or until desired tenderness
Checking on the bean every 10 minutes after the 1st cooking hour
When done, turn off heat and sprinkle on some salt.
Cool the beans, take out what's needed and freeze extra for up to 3 months