Mussel Tagine with Tomatoes and Moroccan Seasonings

In my updated version of this classic recipe, I deviate from the traditional Moroccan approach to mussels, which is to overcook them, causing the shellfish to toughen, and then to cook them even further, which softens the shellfish and allows them to absorb flavorings. Instead, I slowly reduce grated frothy tomatoes with herbs and spices to the consistency of a thick jam and then add broth from some quickly steamed mussels. Once the sauce is ready and the tagine is still very hot, the shell