Draping the trout with lettuce leaves keeps it moist as it poaches. One rule of thumb for cooking fish is to allow 10 minutes to the inch, measuring fish at its thickest point (about halfway down its back).
- 2 (1-lb.) whole trout, cleaned
- Salt and freshly ground black pepper
- 1 bunch fresh mint
- 2 cups dry white wine
- Leaves from 1 head bibb lettuce, blanched
- 1 egg yolk
- 1 tsp. dijon mustard
- 3⁄4 cup corn oil
- Juice from 1 lime
Preheat oven to 350º. Place trout side by side in a large baking dish. Generously season inside and out with salt and pepper, then stuff each cavity with half the mint. Add wine and enough water to the dish to reach halfway up the fish (about 2 cups). Drape lettuce leaves over fish, covering them completely. Poach fish in oven until just cooked through, 25–30 minutes.
Meanwhile, whisk together egg yolk and mustard in a small bowl until thick. Add oil in a slow, steady stream, whisking constantly until all oil has been absorbed. Add lime juice and season to taste with salt; cover with plastic wrap and set aside.
Using a slotted spatula, carefully transfer fish to a clean kitchen towel. Remove and discard heads, tails, and mint, then bone fish, leaving filets intact. Transfer fish to a platter and season to taste with salt and pepper. Serve with mayonnaise and lime wedges, if you like.