Sear lamb in the olive oil in a cast-iron skillet or Dutch oven. Add the onions; saute them for 2 minutes; then add the garlic and saute it for 1 minute. Put in the turmeric, nutmeg, cardamom, crushed red pepper and cinnamon and saute the mixture for 1 to 2 minutes more, being careful not to burn the onions or garlic. Add the tomatoes and veal stock and stir.
Cover the dish and bake at 350 F. for about 1 hour, until the meat is tender and begins to break up. Remove the dish from the oven and add the spinach, stirring until the spinach is wilted and blended in. Allow the stew to cool slightly. Add the yogurt, lemon peel and salt to taste. Sprinkle with roasted pine nuts.