Preheat the oven to 200'C.
Check the fish and clean if there are any fish scales. Season with a pinch of salt and pepper. Heat the oil in a frying pan, then place the fish skin-side down and cook until the skin is crispy. Transfer onto a baking tray and cook in the oven for about 7 minutes.
Cook the puy lentils in water until soft. Drain and leave to a side.
Peel and dice the carrot. Dice the leek and wash to remove any dirt. Then dice the celery stick.
Heat a pan and add the oil. Sweat the diced carrot and celery in the pan, then add the leeks and cook until soft. Add the cognac and flambe. Pour in the stock and bring to boil. Then finish with the cooked lentils and simmer for 5 minutes until the liquid is mostly evaporated. There should still be some moisture in the pan.
Pick the leaves from the parsley and chop. Over a medium heat melt the butter and continue to cook until it turns a golden brown colour. Remove from the heat and add a squeeze of lemon juice. Then mix in the capers along with a pinch of salt and the chopped parsley. Taste and adjust the seasoning to your liking.
Place a spoonful of braised puy lentils onto the centre of the plate. Place the fish on top and drizzle the sauce around.
«Keep a close eye on the butter as you cook your beurre noisette - you want it to be nice and golden brown but not burnt.»