Preheat your oven to 425°F (220°C). Cut the cauliflower into bite-sized florets and toss them with olive oil, salt, and black pepper on a baking sheet. Spread evenly and roast for about 45 minutes, turning halfway through after 25 minutes until golden brown and tender.

While the cauliflower roasts, heat a tablespoon of olive oil in a large pot over medium heat. Add the chopped onion and sauté for about 7 minutes until translucent and fragrant. Stir in minced garlic, ground cumin, sweet paprika, ground sumac, and turmeric, cooking for 1 minute.

Add ¾ of the roasted cauliflower to the pot, combine with the flavors. Pour in the vegetable broth and water, bringing to a boil. Lower the heat and simmer for 5-7 minutes.

Remove from heat and carefully blend the soup using an immersion blender until smooth. For a chunkier texture, leave small bits of cauliflower.

Return the blended soup to low heat, stir in milk or plant-based milk along with lemon juice. Add the remaining roasted cauliflower.

Just before serving, stir in freshly chopped dill. Serve hot with fresh crusty bread or a light salad.