Crush the corn coarsely with 1 cup water. Crush onion, ginger and garlic cloves. Heat oil and butter in a deep non stick pan. Add cumin seeds, cinnamon, black cardamoms and crushed black peppercorns and sauté for 1 minute.
Add crushed onion-ginger-garlic and sauté for 2 minutes. Add refined flour and mix well and sauté for 1 minute. Add corn, 3 cups water, roughly chopped fresh coriander stems, turmeric powder and salt and mix well. Once the mixture comes to a boil, cover the pan and let it cook for 5-7 minutes on medium heat. Keep the spinach leaves one top of the other, roll them and slice into thin strips.
Strain the soup through a thick sieve into a glass bowl, pressing the residue with a ladle to extract all the flavours. Squeeze the juice of a lemon and mix. Place spinach strips in a soup bowl, pour the soup around the spinach and serve hot.