Once the liquid is simmering, add your proteins (mussels, shrimp, scallops, octopus, chorizo). Try to spread them out evenly around the pan. Mussels should go in on their side, hinge side down, so that they open facing upwards. Cook for about 15 minutes or so, with the grill covered, or until the rice is almost done. Try to move the pan around the grill occasionally for even cooking, although depending on your grill this isn’t completely necessary.