According to legend, this seafood soup originated in San Francisco, the creation of Italian-immigrant fishermen who were as skilled with a soup kettle as they were with a net.
Thaw fish and shrimp, if frozen. Peel and devein shrimp. Rinse fish and shrimp; pat dry with paper towels.
In a small bowl, combine pasilla chile peppers and enough boiling water to cover. Let stand for 20 minutes. Remove chile peppers with a slotted spoon, reserving 1/4 cup of the soaking liquid. Remove seeds and stems from chile peppers and discard. In a blender, combine chile peppers and reserved liquid; cover and blend until smooth. Set aside.
Meanwhile, in a large, shallow bowl, combine fish and shrimp. In a small bowl, combine 1/2 teaspoon of the salt and the chili powder; sprinkle over fish.
In a 4-quart nonstick Dutch oven, heat 2 teaspoons of the oil over medium-high heat. Add half of the fish and half of the shrimp; cook about 4 minutes or just until done, gently turning mixture with a spatula occasionally. Remove with a slotted spatula to a clean bowl. Repeat with remaining seafood (add additional oil, if necessary). Chill bowl of seafood until needed (up to 2 hours).
In the Dutch oven, heat remaining 2 teaspoons oil. Add onion, corn, and garlic; cook for 3 minutes, stirring occasionally. Stir in pureed chile mixture, beans, undrained tomatoes, clam juice, wine, the 1 cup water, green chile peppers, and remaining 1/2 teaspoon salt. Bring to boiling; reduce heat. Cover and simmer for 20 minutes. Uncover; add seafood. Simmer, uncovered, for 5 minutes more. If desired, serve with avocado and cilantro. Makes 6 servings.