Prepare the fillet, debone if necessary. To debone, simply drape the fillet over a small mixing bowl that has been flipped upside down. This will cause the bones to poke out so you can easily grab them with your fingers or a tweezers.

Dredge the fillet in the flour, meat side only. Season with salt and pepper.

Put the roughly chopped rosemary (or herb of your choice) into the trout. Pat into it gently.

With the stovetop at medium heat, place a tablespoon of unsalted butter into the pan, and place the trout skin side down and cook for two minutes on each side approximately. (Feel free to add more butter to the pan when you flip the trout to the second side.)

Remove from the heat, and place on a platter. Garnish the platter with fresh sprigs of rosemary or whichever herb you used, as well as slices of lemon. Drizzle the Citron Beurre Blanc on top of the fillet (or you can reserve the sauce, place it in a small pitcher, and let each guest add the sauce to their own fillets).

Over medium-high heat (do not bring it to boil), place the shallot and lemon juice in a sauce pan. Cook and stir until the lemon juice has reduced by half.

Once the lemon juice has reduced to half, remove from the heat, the pan will still be warm, and begin adding two tablespoon of butter at a time and stir constantly until incorporated. Make sure the pan/sauce stays warm, and if it needs to return to the stovetop, do so to keep the sauce warm, but do not bring to boil or it will likely break.

If the sauce breaks, you can add one ice cube and stir until it retains the consistency you want while stirring over medium-high heat. You can also use a touch of heavy cream, but the ice cube would be my recommendation. You can only do this once, but it most definitely can work the first time.

Stir in the remaining butter until fully incorporated. You can keep the sauce warm if you are not serving it immediately, by placing it in a warm water bath. In a large casserole dish, or larger than your sauce pan, place hot tap water - about 1-2 inches. Place the sauce pan, with the sauce into the casserole dish with the water and set aside until you wish to serve it.