In a large Dutch oven or stock pot, heat the oil. Brown the onion and ginger over medium heat until lightly caramelized on all sides, about 4 minutes. Add the cardamom, star anise, cinnamon, cumin, cloves and salt. Toast the spices, stirring once or twice, until fragrant, about 2 minutes. Cover the spice mixture with the water and add any additional veggie scraps you’re using (you can also add a head of garlic or give it a kick with a jalapeno).