Heat the oil.
Add the mustard seeds and fennel seeds. When the mustard sputters, add the ginger and garlic, saute for a few seconds, then add the onions and the bay leaves.
Add a generous pinch of salt and saute on a medium-low flame until the onion turns translucent.
Add the cumin powder, coriander powder, garam masala, green chillies, and turmeric. Stir well.
Add the cooked greens. mix well, and bring to a simmer. Lower the heat and cook for five minutes. Let it cool a little and then transfer to a blender and blend into a smooth paste. Be very careful handling the hot mixture. If you have an immersion blender, this is good time to break it out.
Add the greens paste back to the pan with the cooked chickpeas. Turn on the heat and bring the mixture to a boil. Add water if it's too dry. Add the cashew cream, the lemon juice, and salt to taste.
Serve hot with rice or phulkas.