Over medium hight heat, drizzle some oil in a sauté pan. Once hot, add the pieces of trout fillets. Season with salt and pepper and cook for 2 minutes without touching the fish.
Then, turn the fish and continue to cook for a further 4-5 minutes until cooked through.
In the meantime, add the shallot, garlic, mushroom, celery, and courgette and again let the vegetables sear and cook of one side without shaking the pan. Season well.
Add the butter at this stage and let it start to foam or become like a beurre noisette (brown butter). Add a squeeze of lemon over the fish to deglaze the pan.
Once the fish re cooked, remove from the pan and place on serving dishes with some mash potato. Quick it aside warm.
Add the prawns in the pan to cook them quickly with the vegetables.
Increase the heat to hight and cook stirring once or twice for 1-2 minutes until the prawns are opaque or cooked through. Remove the pan from the heat and serve the prawns and the vegetables over the fish. add a dollop of red pesto and enjoy while hot.