Trout and leek gratin

A classic French oven-baked dish in which gently braised leeks are combined with a creamy sauce and tender trout, finished with a golden-brown cheese crust. Elegant enough for dinner, yet simple enough for a weekday meal.

Serves: 4
Preparation: approx. 20 minutes
Cooking: approx. 30 minutes
Total time: approx. 50 minutes

Ingredients

• 2 large trout fillets (together approx. 400–500 g)
• 500 g leeks
• 200 ml crème fraîche
• 100 ml milk
• 1 teaspoon Dijon mustard
• 60 g grated cheese (preferably Gruyère or Emmentaler)
• 20 g butter
• ½ lemon (zest + 1–2 teaspoons juice)
• Pinch of nutmeg
• Salt
• Freshly ground black pepper

Preparation

• Preheat the oven to 190 °C (conventional heat).
• Clean the leeks: cut away the dark green parts, halve the stalks lengthways and rinse thoroughly under running water. Then slice into half-rings.
• Pat the trout fillets dry with kitchen paper, check for any remaining bones and remove them. Cut the trout into fairly large pieces (about 3–4 cm). Season lightly with salt and freshly ground black pepper.

Method

1. Braise the leeks
   Melt the butter in a large pan over medium-high heat.
2. Let the leeks soften
   Add the leeks, stir, and lower the heat slightly. Put a lid on the pan and gently braise the leeks for 5–7 minutes until softened.
3. Let excess moisture evaporate
   Remove the lid and, if necessary, let any excess moisture evaporate for another 2–3 minutes.
4. Season the leeks
   Season with a pinch of nutmeg, some salt (careful, as cheese will be added) and freshly ground black pepper.
5. Make the cream mixture
   In a bowl, mix the crème fraîche with the milk until smooth.
6. Add mustard and lemon
   Stir in the Dijon mustard, the lemon zest and 1 teaspoon of lemon juice. Taste and add an extra teaspoon of lemon juice if needed, depending on the strength of the lemon.
7. Season the sauce
   Season the mixture lightly with black pepper and, if necessary, a small pinch of salt.
8. Grease the baking dish
   Lightly grease a medium-sized baking dish (for example with a little butter).
9. Spread the leeks in the dish
   Spread the braised leeks evenly over the base of the dish.
10. Place the trout on the leeks
    Place the pieces of trout on top of the leeks.
11. Pour the cream sauce over
    Pour the cream sauce over the top so that the leeks and trout are largely covered.
12. Sprinkle with cheese
    Sprinkle the grated cheese evenly over the top.
13. Bake the gratin until golden
    Bake the gratin in the preheated oven for 20–25 minutes, until the top is golden and the sauce is gently bubbling. The trout should be just cooked but still juicy.
14. Let the gratin rest briefly
    Let the gratin rest for a few minutes out of the oven before slicing.
15. Serve straight away
    Serve straight away, for example with boiled or steamed potatoes, a piece of good baguette and a crisp green salad with classic vinaigrette. Optional: just before serving, sprinkle with a little finely chopped chives or parsley for colour and a subtle herby note.