Preheat oven to 375 degrees F.
Place the flour in a shallow bowl and season with salt and pepper. In another shallow bowl, beat the eggs with the mustard. In a third shallow bowl, place dried mashed potato flakes.
In a large ovenproof saute pan, heat oil.
Dip the steaks first in the flour, then the egg mixture, and finally in the potato. Add the fish to the saute pan and cook for 2 minutes per side. Then place the fish into the oven for 4 minutes, until the fish is cooked through and golden.
To serve, spoon the Lemon Butter Sauce in the center of each plate. Place the crusted steaks in the center of the sauce.
Set a large non-reactive saucepan over high heat. Add the wine, lemon juice, garlic, and shallots. Cook for 5 to 6 minutes or until liquid is reduced by 2/3.
Over low heat, whisk in 6 tablespoons of the butter a few pats at a time. Remove from heat and whisk in the remaining 4 tablespoons of the butter 1 tablespoon at a time. Continue whisking until all of the butter is incorporated into the sauce.
Strain the sauce, pressing all of the liquid into a bowl. Stir in the parsley. Serve immediately, or keep warm for a few minutes until ready to use.