Dice the onion relatively finely and finely chop the garlic, ginger and chili, if using.
Heat a little oil in a pan (around 1tbsp, not olive oil - vegetable or other unflavored is better) and add the onion. Cook for around 3-5 minutes until starting to soften. Add the garlic, ginger and chili, if using, and cook for another minute or two.
Add the cumin and coriander and stir in, cook a minute then add the drained chickpeas, tomatoes, lentils and water. Stir well then bring to a boil.
Cover, reduce the heat to a gentle simmer and leave to cook until the lentils have cooked, around 25 minutes, stirring now and then to avoid it sticking too much.
While the lentils are cooking, chop the spinach relatively small and roughly chop the cilantro. When the lentils are cooked, add both to the pan, stir in and cook a minute until they have wilted down then serve. Can be made ahead and stored a day or two in the fridge.