Season the lamb with salt and pepper. In a large pot heat the oil over medium high heat, then brown the lamb on all sides, about 6 minutes in all. Transfer the lamb to a plate with a slotted spoon. Add the onions and garlic to the same pan and sauté for about 5 minutes over medium heat until the onions are tender and lightly golden.
Add the ginger, coriander and cinnamon to the pot and stir so that the onion is coated with the spices. Add the tomatoes and the water, return the lamb to the pot, and bring to a simmer over medium high heat. Reduce the heat to medium-low, cover the pot, and keep it at a low simmer for about 2 hours, until the lamb is almost tender. Add the squash and simmer for another 45 minutes until the lamb is very tender and the squash is cooked through.
Sprinkle over or stir in the parsley and serve hot.