We chop the onions, celery, and shallot into small pieces, yielding 1/2 cup, 1/3 cup, and 2 tablespoons, respectively. Then we mince our garlic. We heat the remaining 1/4 of wine in a measuring cup in the microwave for 30 seconds. We remove it and add the saffron threads.
In a large pot, we heat the remaining tablespoon of olive oil over medium-low heat. We add the onion and cook for about 5 minutes. Then we add the celery and shallot and cook for another 5 minutes. At this point, we strain the shrimp stock through a fine mesh strainer into a large measuring cup. We have 1 1/3 cups of stock.. We add the garlic to the softened vegetables in the stew pot and when it is fragrant we add the saffron-wine mixture and the fish stock. We sprinkle in some red pepper flakes. We add half the 28-ounce can to a measuring cup, chopping the whole tomatoes with our hands and adding some liquid from the can. We add 1.5 cups of tomato and liquid to the stew. The remainder of the can we pour into a plastic container and refrigerate.
We bring the stew to a boil and add salt and pepper. We lower the heat to a simmer and take the fish and shellfish out of the freezer. We rinse the fish and seafood mix in a colander and add the fish to the stew. We gently poach the fish for about 10 minutes. The fish is nearly done at this point, as we break apart the fillet into smaller pieces. We add the shellfish and cook for about 5 minutes (since it is still a little frozen.) When the fish and shellfish are cooked through, we chop the herbs and add to the stew. We serve immediately.