Original recipe makes 15
1-Place the onion, rinsed beans, jalapeno, garlic, salt, pepper,
and cumin into a slow cooker. Pour in the water and stir to
combine. Cook on High for 8 hours, adding more water as
needed. Note: if more than 1 cup of water has evaporated
during cooking, then the temperature is too high.
2-Once the beans have cooked, strain them, and reserve the liquid.
Mash the beans with a potato masher, adding the reserved water
as needed to attain desired consistency.
Article source : allrecipes.com