For the seafood base: Place the red onion, chile pepper, lemon zest, garlic, parsley, thyme, and bay leaves in a food processor and process ingredients into paste.
For the soup base: In a Dutch oven, heat the extra-virgin olive oil and anchovies over medium-high heat, when the anchovies melt into the oil add the seafood base and stir 3 to 4 minutes then add the celery, potatoes, and red pepper and cover the pot 4 to 5 minutes to sweat them out, stirring occasionally. Deglaze the pot with beer. Add tomatoes and chicken stock and bring to a boil, simmer for 20 minutes or until it has reduced by a third, then turn off the heat, cool and store for a make-ahead meal.
To reheat: Reheat over medium-high heat. Crust up and warm bread in a hot oven. When the stoup comes to a boil, fold or nestle the cod and scallops into the liquid, and return to a bubble, cook for 5 to 6 minutes, until the fish is opaque and cooked through, then turn off the heat. Serve immediately with lots of bread for mopping.