Cut each fillet into a 4-oz. (100-g) rectangle. Refrigerate. Rub the trimmings with salt and refrigerate for 45 - 60 minutes.To make the duxelles, sweat shallot in butter in a saucepan. Add mushrooms, cook 5 minutes and add white wine. Reduce over low heat until no liquid is left. Season with salt and ground black pepper. Refrigerate.In a pan, melt a knob of butter and sweat onion. Deglaze with white wine and bring to a boil. Add mussels to boiling liquid and cover. Cook 4 - 5 minutes until mussels open. Remove mussels from shells and refrigerate. Strain pan juices and set aside.In a pan, bring juices to a boil. Reduce to 3/4 of volume and add white poultry stock. Bring to a boil again and reduce to 3/4 of volume. Add cream and reduce to desired consistency. Add green peppercorns, season and refrigerate.In a pan, cook turnip with minced 1/4 onion and a drizzle of olive oil. Purée in food processor. Add 35% cream and heat slightly. Blend and season. Press through a sieve and refrigerate. In a pan, reduce shallot and white wine over medium heat until no liquid is left. Refrigerate.In a pan, bring water, sugar and lemon juice to a boil. Meanwhile, using a mandolin, slice celery into crescents about 3-mm thick. When syrup comes to a boil, pour it over celery. Marinate at room temperature for 10 minutes. Drain and refrigerate celery.In a pan, sweat 1/2 garlic clove and shallot in drizzling of olive oil. Add milk and bring to a simmering boil. Poach tilapia trimmings 2 minutes in simmering liquid. Drain poached tilapia and beat with 1 1/3 oz. (40 mL) olive oil in a round-bottomed bowl. Season and refrigerate brandade.In a skillet, melt a knob of butter and sweat minced 1/4 onion and 1/2 garlic clove. Add mushrooms and season. Cook until all liquid has evaporated. Add veal demi-glace and cream. Reduce until almost no liquid is left. Adjust seasoning and refrigerate.Cut potatoes with a 1-in. (2.5-cm) round cookie cutter. Pour white poultry stock into a skillet. Add potatoes and season. Bring to a boil. Cover and bake in a 375°F (190°C) oven. When potatoes are done, drain and set aside. Reduce pan juices until almost thickened to coating consistency and set aside.In a small round-bottomed bowl, combine 20 mussels with mustard, green onions, celeriac, wine vinegar and a generous drizzling of olive oil. Season and set aside at room temperature.Heat sauce, turnip purée, duxelles and brandade.Season 4 tilapia fillets with celery salt. In a skillet, cook fillets in a generous bit of butter. Meanwhile, reheat potatoes in their pan juices.Presentation:Place fillet on a slice of prosciutto in the centre of the plate and garnish with a spoonful of duxelles and a spoonful of brandade. Draw a line of purée, add mussels, marinated celery and potatoes. Spoon green pepper sauce over fish and put vinaigrette on the mussels.

4x5 oz (4x150 g) tilapia fillets celery salt to taste Salt and pepper to taste duxelles: butter as needed 1 shallot, peeled and minced 1 lb (454 g) cremini (brown) mushroom 1/4 cup (60 mL) white wine mussels 1/4 onion, peeled and minced fine 1 cup (250 mL) white wine 1 lb (454 g) washed mussels green pepper sauce butter as needed 1/4 cup (60 mL) white poultry stock 3/4 cup (190 mL) ferme des 3 vallées 35% cream 1 tsp. (5 mL) green peppercorns in brine, rinsed and drained turnip purée 9 oz (250 g) turnip, peeled and diced 1/4 onion, peeled and minced fine olive oil as needed 1/4 cup (60 mL) ferme des 3 vallées 35% cream celery 1/4 cup (60 mL) water 5 oz (150 g) sugar 8 tsp. (40 mL) lemon juice 1/2 celery stalk, washed and peeled poached tilapia trimmings 0.500 garlic clove, peeled and chopped 1 shallot, peeled and minced olive oil as needed 2 cups (500 mL) organic 2% milk 8 tsp. (40 mL) olive oil mushroom 1/4 onion, peeled and minced fine 1/2 garlic clove, peeled and chopped butter as needed 5 tsp. (25 mL) veal demi-glace veau 5 tsp. (25 mL) ferme des 3 vallées 35% cream 4 thin slices of prosciutto potato 4 yukon gold potatoes 1 cup (250 mL) white poultry stock celeriac vinaigrette 1/2 tsp. (7 mL) grainy mustard 1/8 green onion, sliced very fine 1/2 lb (225 g) celeriac, peeled, diced fine and blanched 1 Tbsp. (15 mL) tarragon white wine vinegar sufficient quantity, olive oil