On a medium burner, heat oil on a medium flame in a big enough wok or pot. Add the bay leaf and cumin seeds. Sizzle for 5-10 seconds, taking care not to burn the seeds.
Add the spinach puree and reduce the flame to low.
Next, add the salt (be mindful of the salt that was added while cooking the kidney beans), turmeric, chilli powder and coriander powder.
Mix, cover and cook on low-medium flame till the spinach is cooked and the oil separates and floats on the top (approximately 10 minutes). Keep stirring in between to make sure it does not stick to the bottom of the pot.
Once the spinach is cooked, add the garam masala and mix.
Next add in the cooked kidney beans along with the water in which it was cooked. With the help of a spoon, press a few kidney beans against the pot side. This helps to thicken the curry and adds flavor as well.
Cover & continue cooking on low flame for another 15-20 minutes till the oil floats on top again. Keep stirring in between.
Taste and add seasoning if required.
Add hot water if required to adjust the consistency. The curry will thicken as it cools down.
Switch off the gas and remove from heat. Cover and let it rest for 5-10 minutes for the flavors to blend.
Serve with rice, roti, paratha, naan, flatbread or even toast.