This peppery and slightly spicy sweet potato soup packs a punch with two types of ginger and a silkiness from pureed white beans! Make the full batch even if you're only cooking for a small number of people as it freezes and reheats beautifully.
Preheat oven to 200°C/400°F. Arrange the sweet potatoes on a parchment-lined baking sheet. Drizzle with 1 tbsp of olive oil and season with salt and pepper. Roast for about 25-30 minutes, or until lightly browned and very tender.
Meanwhile, add 3 tbsp of olive oil to a large saucepan and set over medium heat. Once shimmering, add the carrot, onion, celery and cilantro stems & ginger. Season with a generous pinch of salt and cook, stirring frequently, until very soft, the vegetables are beginning to brown and fond begins to collect on the bottom of the pan, about 10 minutes.
Add the tomato paste, garlic, cardamom, turmeric, ground ginger, cinnamon, cloves and cayenne pepper along with a generous grind of black pepper. Stir into the mixture and cook until fragrant and darkened, about 2 more minutes.
Add the roasted sweet potatoes and stir to coat in the mixture.
Pour over the vegetable stock and soy sauce. Bring to a gentle simmer and allow to simmer for about 5-10 more minutes.
Transfer the soup to the jar of a blender or use a stick blender to puree the soup until smooth. If using a traditional blender, you may need to work in batches before returning the soup to the pot.
Stir in the pureed cannellini beans, maple syrup and apple cider vinegar. Bring to a simmer and taste to adjust for seasoning, adding more salt and pepper where needed. Serve, topping with the cilantro leaves and perhaps some toasted nuts.