One of the best ways to guarantee perfectly cooked beans — ones that emerge creamy and tender instead of crunchy or mushy — is cooking them ever-so gently over low, steady heat. Hmm... low and steady heat, you say? Sounds to me like a job for the slow cooker.
For small batches of beans, a pound or less, I think 3 1/2-quart or smaller slow cooker does the best job. When I use my big 7-quart slow cooker, I usually cook 2 pounds or more and freeze what I don't use right away. Beans freeze beautifully! I freeze them in 2-cup portions, which makes it easy to pull out just what I need for a recipe.
With beans made in the slow cooker, pre-soaking them is far less important than with other cooking methods. The long cooking time means that those beans will definitely soften! However, I am a believer that soaking the beans removes some of the enzymes that causes intestinal discomfort, so I usually stick to the practice of soaking them overnight. If you're not as bothered after eating beans, then you can certainly skip this step.
Add any aromatics, like bay leaves or garlic, at the beginning of cooking. Their flavors will gently infuse the beans and their cooking liquid over the long cooking time. I also add a teaspoon of salt at the beginning of cooking — a controversial tactic, I know! This is a trick that I picked up from Cook's Illustrated: a little salt added at the beginning of cooking actually helps keep the beans intact and prevents "blow out" beans. I've tried this for several batches of beans now and have now adopted it as regular practice.
The first time or two that you cook beans in the slow cooker, it's best if you can be around to check on them toward the end of cooking. Some slow cookers — and some beans! — will cook more quickly or slowly than others. Until you're familiar with how long beans typically take in your slow cooker, start checking them around 5 hours and then every half hour or so after that until they're done.
Cover the pot and cook on low for 6 to 8 hours.
How To Cook Beans in the Slow Cooker
What You Need
Any amount of dried beans (Other than lentils; see How to Cook Lentils)
2 teaspoon salt per pound of beans, divided
Aromatics, like a bay leaf, peeled garlic, minced onion, or dried herbs (optional)
Smoked meat, like ham hock or smoked turkey leg (optional)
3 1/2-quart or smaller slow cooker, for 1 pound of beans or less
5-quart or larger slow cooker for 2 pounds of beans or more
Soak the beans overnight (optional): Rinse the beans under cool, running water and remove any shriveled or unappetizing-looking beans. Transfer them to a bowl and cover with several inches of clean water. Let sit overnight. Drain before cooking.
→ Safety Note: If you are cooking kidney beans, boil them for 10 minutes before cooking. This neutralizes a toxin called phytohemagglutinin (say that 3 times fast) that can cause acute digestive distress.
Transfer the beans to the slow cooker: If you haven't already done so, rinse and pick over the beans. Transfer the beans to a slow cooker.
Add aromatics: Place the aromatics on top of the beans.
Cover with water: Pour enough water over the beans to cover them by about 2 inches. Add 1 teaspoon of salt and stir to dissolve.
Cook on low for 6 to 8 hours: Cover the pot and cook on low for 6 to 8 hours. If you this is your first time cooking beans or you're cooking an unfamiliar kind of bean, begin checking the beans after 5 hours and then every 30 minutes until they are cooked to your liking. Beans generally finish cooking in 6 to 8 hours. When the beans are soft but still a little more firm than you'd like, add the second teaspoon of salt and continue cooking until done.
Cool and store: Cool the beans and then store them in the fridge for a week or in the freezer for up to 3 months.
• For a quicker cooking time, or if your beans are older than a year, try soaking the beans overnight with a brine solution of 1 1/2 tablespoons of salt mixed into 8 cups of water.