1. In a flameproof glass, enamel or stainless-steel baking dish large enough to hold the fish in one layer, combine the red wine, olive oil, water, onions, mint, rosemary, thyme, bay leaf, peppercorns and salt, and stir thoroughly.
2. Wash the trout under cold running water and dry them completely with paper towels. Then place them in the marinade, turning them about to coat them thoroughly. Marinate at room temperature for about 30 minutes, turning the trout over after 15 minutes.
3. Preheat the oven to 350°. On top of the stove bring the marinade to a simmer, then lay a sheet of wax paper or foil lightly over the baking dish. Bake in the middle of the oven for 20 minutes, or until the fish is firm to the touch. Be careful not to overcook.
4. With a slotted spatula, transfer the fish to a heated serving platter and cover loosely with foil to keep them warm. Strain the cooking liquid through a fine sieve into a small saucepan, pressing down hard on the onions and herbs with the back of a spoon before discarding them.
5. Whisk about ¼ cup of the liquid into the beaten egg yolks, then whisk the mixture into the remaining liquid in the pan. Heat slowly, whisking constantly, until the sauce thickens lightly. (Do not let it come anywhere near a boil or it will curdle.) Taste for seasoning.
6. Pour the sauce over the trout or serve the sauce separately. Traditionally the trout are accompanied by hot, freshly boiled potatoes.
