To sauté pork tenderloins, cut them into rounds (noisettes) about 3/4-inch thick, brown them over high heat, and then continue cooking them until they are firm to the touch. Here, they are served with a sauce made with prunes soaked in wine, a little meat glaze (if you have it), and some cream.
*To make meat glaze, put 5 quarts beef broth in a pot on the stove top and bring to a gentle simmer. Move the pot slightly off center of the burner and adjust the heat so the liquid bubbles gently on one side (a bubble rises only every second or two). Simmer gently, frequently skimming off the fat and froth as they accumulate with a ladle, until the broth is reduced by about half. Remove from the heat and strain through a fine-mesh strainer into a smaller pot. Return the broth to the stovetop and continue reducing the same way. When it is again reduced by half, strain it into a smaller pot and continue reducing until you have about 2/3 cup. Transfer to a jar or plastic container, let cool, cover, and refrigerate for up to 3 months or freeze indefinitely. If you prefer to make and use demi-glace, only reduce the broth to 1 1/3 cups and use twice as much in recipes calling for meat glaze. Additionally, you can purchase meat glaze online here.
In a small bowl, pour the wine over the prunes and let soak for at least 1 hour or up to overnight.
Trim the silver skin off the tenderloins. Cut the tenderloins into rounds about ¾-inch thick. Season the rounds on both sides with salt and pepper.
In a sauté pan just large enough to hold the rounds, heat the olive oil over high heat. When it smokes, add the pork rounds and brown, turning once, for about 3 minutes on each side, or until they feel firm to the touch. If they start to get too brown, turn down the heat. Transfer the pork rounds to a warmed platter and set aside in a warm spot. Pour the fat out of the pan.
Drain the prunes, reserving the wine and prunes separately. Measure out ½ cup of the wine. Return the pan to high heat and add the ½ cup wine and the prunes. Deglaze the pan, scraping up any brown bits on the bottom of the pan with a wooden spoon, then stir in the meat glaze, if using. Boil until the wine is reduced by about ½; if you have added the glaze, the sauce will develop a lightly syrupy consistency. Add the cream and boil until reduced to a light sauce consistency. Season with salt and pepper.
Arrange the pork rounds on warmed plates and spoon the sauce and prunes over the top.