Created by Red Apple Guy on May 18, 2015
Step 1: Drain & rinse the beans and transfer them to a big pot. Add 4 cups of cold water and bring to a boil for about 3 minutes. Skim off white foam from the top. Lower the heat to medium, & add the onion, celery, carrot, thyme, & tarragon. Cover & simmer for 45 minutes, until beans are very tender.
Step 2: Add beans and water to cover (by 1 to 2 inches) to a 2 to 3 1/2 quart crock (a 2 quart crock will be completely full). Set the cooker on low and add the onion, celery, carrot, thyme, & tarragon. Cover & cook for 5 to 6 hours until beans are very tender.
Step 3: Remove onion, carrot, & celery. Discard or save it for a veggie broth. Continue simmering on low while you prepare the other vegetables. The beans should be thick like a stew, not soupy. If it's too liquidy, tip the lid some to allow steam to escape and stir occasionally. This venting from the lid may take hours for a slow cooker.
Step 4: About 10 minutes before the beans are done, place the garlic & 2 tbsp olive oil in a cold skillet, and heat over medium, allowing the garlic to sizzle for 30 seconds. Add the chopped leek & saute until it's soft, a couple minutes. Add the cooked leeks to the beans. Add the remaining 2 tbsp of oil (or a little less), and add the mushrooms. Sprinkle them lightly with 1/2 tsp salt and saute until most of the mushroom liquid is gone, between 8 and 12 minutes. Add the mushrooms to the beans when most of the liquid is evaporated.
Step 5: Turn off the heat & season with remaining salt & pepper. Let the beans stand for a few minutes before serving.