Heat a large, wide-based pot with a drizzle of oil. Add the onions and carrots with a generous pinch of salt and cook for 3-4 minutes until just starting to soften.
Tip in the finely chopped red chilli (if you like it fiery, add the seeds too), reserving some to decorate. Add the curry powder, ground cumin, red lentils and coriander stalks. Stir well and cook for a minute or so until spices start to release fragrance.
Dissolve stock in 700 ml of boiling water and add it to the lentil mixture. Stir, reduce the heat to low, cover with a lid and leave to simmer for 15-20 minutes or until lentils are cooked and carrots are tender.
In the meantime, cut up your bread roll into bite-sized pieces. Spread them on a tray in a single layer, drizzle with olive oil and season. Pre-heat your grill to medium heat and place the bread chunks under the grill to dry and crisp up. Keep an eye on them - they can burn in a jiffy!
Once the carrots and lentils are cooked, remove from heat, use a stick blender or pour into a liquidiser and pulse until it's thickened slightly, but some chunks of carrot remain. Add coriander leaves and juice of ½ a lime. Season to taste.
To serve, divide the soup into two bowls, swirl the cream to create a pretty pattern. Garnish with the saved chilli, nigella seeds and croutons. Serve with a lime wedge on the side!