Preheat the oven to 220°C.
Season the inside of the trout with salt and pepper.
Stuff the trout cavities with herbs and lemon slices.
Fry the trout in foaming butter for 1 to 2 minutes per side.
Transfer trout to a tray and bake for 4 to 5 minutes until cooked.
Rest the fish for one minute, then remove skin and heads.
Heat butter in a pan until it turns a nut-brown color.
Stir in lemon juice, almonds, capers, herbs, and seasoning then remove from heat.
Whisk oil, vinegar, and mustard together in a small bowl.
Toss the salad leaves with the dressing just before serving.
Serve trout topped with brown butter sauce alongside the salad.