Combine water, the 1/4 cup lemon juice, onion, salt, peppercorns, and bay leaves in a 12-inch skillet. Bring to boiling; add the salmon steaks.
Return just to boiling. Cover and simmer for 10 to 12 minutes or until fish flakes easily when tested with a fork. Lift fish from the cooking liquid with a slotted spatula. Cool fish slightly. Place in a storage container; cover and chill for 2 to 8 hours.
For sauce, combine mayonnaise dressing or salad dressing, parsley, snipped or dried dill, lemon peel, the 2 teaspoons lemon juice, and garlic in a small container. Stir in enough buttermilk to reach desired consistency. Cover and chill. Seal lemon slices and dill sprigs in separate self-sealing plastic bags.
Transport all ingredients in an insulated cooler with ice packs. To serve, arrange fish on a platter. Drizzle some of the sauce over the fish; garnish with lemon slices and dill sprigs. Pass remaining sauce. Makes 6 servings.