Boil potatoes in salted water 10 minutes or until tender; drain.
Heat oil in a large nonstick skillet over medium-high heat. Add onion and next 3 ingredients; cook 3 minutes or until almost tender. Add sausage, and cook 3 minutes. Add clam juice and tomato paste; bring to a boil. Add clams, reduce heat, and simmer 3 minutes. Add cod, and simmer, covered, 4 to 5 minutes or until fish flakes easily when tested with a fork. Add potatoes, and cook 1 to 2 minutes or until heated through. Drizzle evenly with lemon juice before serving.
Wine note: A lovely, all-purpose wine to pair with this cod recipe is the Chateau Ste. Michelle 2004 Horse Heaven Sauvignon Blanc ($18). If you want to expand your vino repertoire, try Rosé of Cabernet Sauvignon, 1+1=3, 2004, Penedes, Spain ($12), recommended by Michael Flynn, wine director and sommelier for Kinkead's Restaurant in Washington, D.C.