Quenelles with Watercress Sauce

Name: Quenelles with Watercress Sauce
Prep time: 40 min
Cook time: 2 h 45 min
Total time: 2 h 45 min
Yield: 4 portions
Ingredients: 375 g white fish fillets, skinless; 1 tsp fine sea salt; ¼ tsp ground white pepper; ½ tsp ground nutmeg; 100 g unsalted butter; 30 g unsalted butter; 100 g milk; 50 g plain flour; 1 medium egg; 1 egg yolk; 2 egg whites; 600 g water; 1 Tbsp cornflour; 100 g single cream; 2 shallots; 30 g unsalted butter; 150 g watercress; 200 g water; 100 g natural yoghurt; 1 Tbsp chicken stock paste; ½ lemon; ground black pepper