For the lamb: Combine the wine, lemon juice, olive oil, garlic, lemon zest, oregano, rosemary and pepper in a blender and blend until smooth. Pour half the mixture over the lamb and turn to coat completely. Cover and marinate in the refrigerator for at least 8 hours and up to 24 hours. Refrigerate the remaining mixture to use for basting while the meat cooks.
One hour before grilling, remove the lamb from the refrigerator and the marinade and let sit at room temperature.
Preheat a gas or charcoal grill with a rotisserie attachment to high heat.
Sprinkle the entire lamb with salt and pepper and attach the lamb to the rotisserie according the manufacturer's directions. Roll up and tie with butcher's twine at 1-inch intervals. Grill until the lamb reaches an internal temperature on a meat thermometer of 170 degrees F, 1 hour 15 minutes to 1 hour 30 minutes for the gas grill, and 1 hour 45 minutes to 2 hours for the charcoal grill. The cooking time will depend on the type of grill and how hot your charcoal is. Baste the meat frequently with the reserved wine mixture. Remove from the rotisserie, put on a large cutting board and rest for 15 minutes.
Slice the lamb across the grain into paper thin slices. Place several slices of lamb in the center of each flatbread, top with a few Grilled Plum Tomatoes, drizzle with the Vinaigrette, scatter fresh oregano on top, and top with Radish Tzatziki.
Grilled Plum Tomatoes:
Heat a grill to medium-high. Brush the tomatoes with oil and season with salt and pepper on both sides. Grill until slightly charred and soft. Flip and grill the other side until slightly charred and soft.
Whisk the vinegar, lemon juice, mustard, honey and salt and pepper. Slowly whisk in the olive oil until emulsified.
Place the radishes and onions in a medium strainer. Place a small plate on top and let sit over a bowl for 30 minutes to drain the liquid.
Transfer the drained radish mixture to a medium bowl and add the yogurt, garlic, dill, lemon zest, salt and pepper. Cover and refrigerate for at least 30 minutes and up to 1 day before serving.