Heat broth in a large pot. Once hot, stir in saffron threads.
Rinse fish and shrimp, then dry on paper towels. Sprinkle with sea salt and let sit for ten minutes.
In a small bowl, combine parsley, garlic, thyme, and a pinch of sea salt. Stir to combine. Add paprika and stir to form a paste, adding water if necessary.
Heat 6 Tablespoons of oil in a 15-inch paella pan over medium high heat. Add the fish and cook until browned, about 1 to 2 minutes. Remove fish to a plate and set aside.
Add remaining 2 Tablespoons of oil to the pan, then add the grated onion, scallions, and bell pepper. Cook until the vegetables are slightly softened. Stir in the tomato and cook until sauce thickens, 2 to 5 minutes.
Pour in the broth and bring to a boil.
Sprinkle the rice evenly across the pan. Boil for 3 minutes, stirring and rotating the pan occasionally.
Add the cod back into the pan.
Stir in the parsley/paprika paste. Do not stir after this point.
Lower the heat and simmer until rice mixture is no longer "soupy", but not dry, about 10 minutes.
Arrange the shrimp, clams, and seafood mixture over the rice, placing the clam shells so they will open facing up.
Cook, uncovered, for 15 to 20 minutes until the rice is almost cooked.
Remove the pan from heat and cover with foil. Let rest for 10 minutes.
Garnish with lemon wedges and serve with alioli.
Substitute chicken broth for seafood broth if you can't find it*Seafood Medley contains calamari, mussels, octopus, and shrimp, and can be found in the frozen seafood section that is usually near the seafood counter.