Heat a skillet over medium-high heat and add the lamb to the pan. Cook for 3 minutes, or until browned, breaking apart the lamb into crumbles with your spatula/wooden spoon. Remove lamb from skillet.
Add oil to the same pan and sauté onion for 2-3 minutes then stir in garlic, cumin, dried oregano, salt, and ground cinnamon. Stir to mix well then stir in the 1/2 cup of water and diced tomatoes. Bring to a simmer and then stir in the cooked lamb. Cover, reduce heat, and simmer for 5 minutes. Stir in the lemon juice.
Split the two pitas into 2 rounds. Place pita rounds on a baking sheet and broil 1 minute on each side, or until crisp. Make sure you watch it carefully!
Spread 2 tbsp. of hummus on each round, top with ground lamb mixture and garnish with parsley and pine nuts.