In a 5- or 6-qt. slow cooker, combine cauliflower, vegetable stock, 1/2 cup almonds, 1/2 cup cilantro and the next seven ingredients. Cook, covered, on low until cauliflower is tender, 6-8 hours., Puree soup using an immersion blender. Or cool slightly and puree soup in batches in a blender; return to slow cooker and heat through. Serve with remaining almonds and cilantro and, if desired, additional harissa.