Place the lentils and rice into a large pot. Add 4 cups of water, 1 teaspoon of salt and 1/2 teaspoon of turmeric and bring to the boil over medium high heat. Reduce heat to medium, cover and cook until the lentils and rice are tender, 15 to 18 minutes. Transfer the rice, lentils and liquid into a bowl.

Place a large pot (you could use the same pot as you cooked your rice and lentils) on medium high heat. Add the butter, oil or ghee and heat until the butter/ghee has melted or the oil is shimmery, 30 to 60 seconds. Add the cumin seeds, ginger, chili, and curry leaves (if using) and stir until fragrant, 30 to 60 seconds. Add the onion and stir until golden brown around the edges, 3 to 4 minutes. Add the tomatoes and season with about 1 teaspoon of salt and a big pinch of black pepper. Stir until the tomato has cooked down and syrupy, 3 to 4 minutes. Add the remaining 1/2 teaspoon of turmeric, ground cumin, ground coriander, amchur powder, and the cooked lentils and rice, along with the spinach. Stir until the spinach has softened, 4 to 5 minutes - if the mixture feels a bit thick, add 1/2 to 1 cup more water to loosen it up. Add the garam masala and chopped cilantro and stir. Turn off heat.

To make the tadka, place a skillet (frying pan) on medium high heat. Add the vegan butter, neutral oil or ghee and when melted or shimmery, add the onion, cumin seeds, dried chilies and curry leaves (if using). Reduce heat to medium and cook until the onions are golden and tender, 6 to 8 minutes. Add garlic and stir for 1 minute.

To serve, ladle the khichdi into bowl and top each with the tadka, if using, and more chopped cilantro/coriander.