Add in the lentils and stir thoroughly before adding in the vegetable stock and lemon. Cover and let cook on low heat for about 15-20 minutes until the lentils are about three quarters of the way cooked.
Taste the broth and adjust seasonings as needed with salt, pepper and additional lemon if you like things extra tangy.
Add in potato cubes and spinach then cover and cook until lentils are tender and the potato can be pierced with knife easily, about another 15 minutes.
Recipe by One Arab Vegan at https://www.onearabvegan.com/2016/04/lentil-spinach-and-lemon-stew/