Place the pepper under a very hot broiler, turning occasionally for about 25 minutes, until blackened on the outside and completely soft. Transfer to a bowl, cover with plastic wrap, and allow to cool. Peel the pepper and discard its skin and seeds. Place a dry frying pan over low heat and lightly toast the coriander, cumin, and caraway seeds for 2 minutes. Remove them to a mortar and use a pestle to grind to a powder. Heat the olive oil in a frying pan over medium heat, and fry the onion, garlic, and chiles for 10 to 12 minutes, until a dark smoky color and almost caramelized. Now use a blender or a food processor to blitz together all of the paste ingredients until smooth, adding a little more oil if needed. Store in a sterilized jar in the fridge for up to 2 weeks or even longer.