Heat your oven to 200°C/Fan 180°C/Gas 6. Place a roasting tin on a shelf to warm. Peel the carrots. Cut into 3cm chunks. Toss with 1 tbsp oil and some seasoning. Add to the tin. Cook for 25 mins.
While the carrots roast, slice the pepper into strips. Discard seeds. Peel and slice the onion. Add them to the tin with the garlic cloves. Toss together. Roast for 20 mins or till everything is tender.
While the veg roast, dissolve the stock cube in 600ml boiling water. Halve the chilli. Scoop out the seeds. Roughly chop it.
Take the veg out of the tin. Use a fork to squash the garlic cloves out of their skins. Tumble the veg, garlic and chilli into a blender. Add ½ tsp each paprika and cumin. Pour in the stock and blitz till smooth (or use a hand-held blender to blitz).
Roughly chop the parsley leaves. Zest the lemon. Stir most of the zest into to the soup and squeeze in the juice. Taste and add seasoning if needed.
Ladle the soup into warm bowls. Top with the parsley and the remaining lemon zest to serve.