In ether a big pot on the stove or your pressure cooker, saute the onion in olive oil for a few minutes. Add salt, beans, garlic cloves and enough water to cover the beans by a couple inches. Cook until the beans are soft (about 25 minutes in the pressure cooker or 1 hour on the stove) See our guide to cooking heirloom beans.
Preheat oven to 350 degrees.
Cut the cauliflower into florets, including the stem. Toss them in olive oil, dust with salt and roast on parchment lined baking sheet for 20-30 minutes until soft, watching closely to see that it doesn't brown. If you start to see browning tent with aluminum foil. This will keep your soup from turning brown.
Remove all but a handful of the smaller more attractive florets that you will use as a garnish. Choose the biggest and least browned cauliflower for the soup base and the smaller more browned ones for the garnish. Place the garnish florets back in the oven and turn up the heat to get them beautifully brown and caramelized around the edges.
Working in batches in your blender or food processor blend the beans including the liquid and everything in the pot with the roast cauliflower, white pepper and vinegar. Blend on high until smooth, adding additional water if it is too thick. Taste and add additional salt and pepper to taste.
Ladle the soup into bowls and top with a generous sprinkle of za'atar and sumac. Place the roasted cauliflower you set aside on top of the soup and then drizzle additional olive oil on top. Serve immediately.
This beloved Italian classic is a testament to the country's artful simplicity in the kitchen. As we delve into this cherished recipe, we'll honor the time-honored traditions of Italian cuisine by starting with dried cranberry beans, which infuse the dish with unparalleled depth of flavor and an exquisite, creamy texture.
In the Basque region of France they don't soak their signature Tolosa beans, they slowly braise them with just water, salt and olive oil. Time and heat to transform even the dense beans from dry to creamy masterpieces. This method works just as well for all heirloom beans! Read more about my bean braising experiments...