Thaw fish, if frozen. Preheat oven to 450 degrees F. Line a shallow baking pan with foil; set aside. Rinse fish; pat dry with paper towels. Arrange fish in a single layer in the prepared baking pan. Sprinkle with salt and black pepper. Bake for 10 to 12 minutes or until fish flakes easily when tested with a fork.
Meanwhile, for salsa, in a medium bowl combine tomatillos, avocado, pineapple, sweet pepper, cilantro, lime juice, oil, and adobo sauce. Spoon salsa over fish. If desired, serve with lime wedges.