Prep. While the meat is grilling, you can make the sauce on a burner indoors or out. Assemble the salt, pepper, and flour in a bowl. In a measuring cup, combine the white wine, sherry, and lemon juice.
Build the sauce. In a frying pan melt the butter on low, then whisk in the flour mixture, turn the heat to over medium, and cook, stirring often, until all the flour is dissolved and starts to turn tan. Wait til it turns color, about 5 minutes. Turn off the flame so you don't have a flareup when you add the wine. Now add the wine mix, stir, and crank it to high. Cook the sauce, whisking every 2 minutes or so until it is slightly thick, but not syrupy thick. If the sauce is too thick, add a splash of water.
Add capers. When the meat is done, add it and the capers to the sauce. Don't add the capers too early or they will disintegrate.
Serve. Spoon a pool of the sauce on each dinner plate, then lay the meat on top of the sauce. Garnish with fresh parsley. If there's extra sauce, put it on the rice, which is a natural piccata side dish.