Rinse the red lentils thoroughly under running water until the water runs clear.
In a large pot, heat some oil over medium heat and add the cumin seeds. Allow them to sizzle for a minute.
Add the chopped onions, garlic, and ginger to the pot and sauté until the onions are soft and translucent.
Stir in the ground turmeric, coriander, and garam masala. Cook for another minute until fragrant.
Add the rinsed red lentils and vegetable broth/water to the pot. Bring to a boil, then reduce heat and let it simmer for about 20-25 minutes or until the lentils are soft and the mixture has thickened.
If using coconut milk, stir it in at this stage for a creamier texture.
Season with salt and pepper to taste.
Add the fresh spinach and cook for another 2-3 minutes until the spinach wilts.
Adjust seasonings as needed.
Serve hot with cooked rice and homemade naan bread