3. Add the onion, tomatoes, and tomato paste, and continue to cook, stirring, for 4 minutes, or until the onions are limp. Add the garlic and cook for another minute. Add the pumpkin, chile (if using), and chicken stock, and bring to a simmer. Reduce the heat to low, and simmer gently for 2 hours or more, or until the meat is very tender. Stir in the cilantro and serve with lots of rice. Serves 4.