Heat the oil in a large pot over medium heat. Add the chopped onion and sauté for 5-6 minutes, until it becomes translucent.
Add the minced garlic and grated ginger to the pot and cook for another minute, until fragrant.
Add the beef cubes to the pot, season with salt and pepper, and cook for 6-8 minutes until the beef is browned on all sides.
Add the ground cumin, coriander, turmeric, cinnamon, and chili powder. Stir well to coat the beef in the spices, and cook for 1-2 minutes until the spices are fragrant.
Stir in the tomato puree and cook for 1 minute, then add the water (or beef broth). Bring to a simmer, cover with a lid and let simmer on low heat for about an hour.
Add the cubed pumpkin to the pot along with the coconut milk. Stir to combine, cover with a lid, and let it simmer for another hour, or until the beef is tender and the pumpkin is cooked through
Taste and adjust seasoning if needed. Serve the curry over cooked rice, and garnish with fresh basil leaves