Set a large saute pan over high heat and add the oil. Sprinkle the lamb with salt and pepper. Add the lamb to the pan along with the garlic and saute until just cooked through, 3 to 4 minutes. Add the oregano and pepper flakes and stir. The lamb is done when browned all over but still tender. Transfer to a dish and set aside.
Set the pan back over the heat and reduce the heat to medium. Add the onions, roasted peppers and mushrooms to the pan. Season with salt and pepper. Saute until the vegetables begin to soften, stirring occasionally, about 5 minutes.
Deglaze the pan with the wine, scraping up any browned bits. Stir in the olives, capers and lemon zest. Bring to a simmer and reduce by two-thirds, 3 to 5 minutes. Season with salt and pepper. Return the lamb to the pan and stir together to incorporate the flavors and heat through.
Serve the lamb with rice pilaf and garnish with the parsley.