Slice salmon into small pieces. Cut 4 thin slices from the lemon. Place fish stock, wine, salt, pepper and lemon slices in a saucepan and bring to a boil.
Add fish pieces, cover and cook over low heat 3 to 4 minutes. Remove from pan and let cool. Reserve liquid.
Place peas and stock in a small saucepan and bring to a boil. Cook peas 3 to 5 minutes; do not overcook. Drain and let cool.
Tear lettuce leaves into small pieces and divide among serving plates. Beat mayonnaise, sour cream, mustard, sugar, salt and pepper with 4 tablespoons fish liquid in a bowl until creamy. Stir in chopped dill.
Arrange salmon and peas on lettuce. Drizzle with dressing. Cut remaining lemon into thin slices. Garnish salmon salad with lemon slices and dill sprigs.
Tip: When buying salmon fillets, check that the flesh is moist and shiny and bounces back when pressed. It should have a pleasant sea smell with no browning around the edges.
Per serving: 368 calories, 24 g protein, 24 g total fat, 11 g saturated fat, 100 mg cholesterol, 12 g carbohydrate, 5 g fibre