Line a baking tray with aluminium foil. Toss the cauliflower with 2 tbsp olive oil, cumin seeds, turmeric powder, and harissa until evenly coated. Spread in a single layer and bake at 180 C/ 360 F for 45 - 50 mins, or until they’ve browned. Remove and set aside. *Taste and check the fieriness of the harissa at this stage; add more if you'd like and return to the oven for 5 more minutes.
Pour 1 tbsp of olive oil in a pot and sauté the onion and garlic until translucent. Add the roasted cauliflower along with any of the remaining cumin on the foil to the pot, and pour in 2 cups of water. Season with pepper and salt. Cover and bring to the boil, then simmer for 10 - 15 minutes, until the florets and tender. Take off the heat and let it cool slightly.
Once cooled, add to a blender/use an immersion blender and blend until smooth. Check seasoning and add milk and more water to get the right consistency. Return the soup to a clean pot and gently reheat. Best served hot.
Recipe by The Blurry Lime at https://www.theblurrylime.com/appetizers/roasted-cauliflower-and-harissa-soup/