Make the harissa by heating a griddle pan (or ordinary frying pan). Add the whole red peppers and cook for 15 minutes, turning occasionally. The skins will blacken and start to lift. Place the peppers in a plastic bag, seal the bag and set aside for a while (this encourages them to 'sweat', making it easier to remove their skins). When cool enough to handle, remove the skin, cores and seeds from the peppers and place the flesh in a blender or food processor.
Remove the skin, cores and seeds from the red chillies in the same way and add the chilli flesh to the blender, together with the garlic, coriander and caraway seeds and olive oil. Process in the blender to a smooth paste. If not required immediately, place the harissa in a sealable container and pour a thin layer of olive oil over the top. Cover with a lid and refrigerate.
Clean the griddle pan (or ordinary frying pan) and reheat it. Place the onion in a bowl, add the paprika and cumin seeds and mix together. Rub the onion and spice mixture into the chicken breasts. Cook the chicken for 10 minutes on each side, turning once. When cooked, remove from the pan.
Place the coriander in a bowl and add the lemon juice, olive oil and a little seasoning. Add the chicken to the bowl and toss well. Serve with rice and the harissa.