In a large skillet, heat the olive oil. Add the onion and bell pepper, season with salt and cook over moderate heat, stirring occasionally, until softened, about 7 minutes. Stir in the paprika and coriander and cook until fragrant, about 1 minute. Stir in the <em>harissa</em> and tomato paste and cook over low heat for 3 minutes. Add the tomatoes and their juices and simmer over low heat until the sauce has thickened, about 20 minutes. Stir in the parsley and cilantro and season with salt.