Rinse the green moong dal under cold water until the water runs clear.

In a saucepan, add 3 cups of water and the rinsed moong dal.

Bring to a boil over medium-high heat.

Reduce the heat to low and let the lentils simmer until they are tender, stirring occasionally, for about 25-30 minutes.

In another pan, heat oil over medium heat.

Add the cumin seeds and fry them for about a minute until they become aromatic.

Add the chopped onion, minced ginger, minced garlic, cumin powder, coriander powder, and garam masala powder (if using) to the pan.

Cook, stirring constantly, for about 5 minutes until the onions are softened.

Add the sliced tomatoes to the pan.

Cook, stirring constantly, for another 5 minutes until the tomatoes soften.

Once the lentils are cooked, add them to the pan along with 3 cups of water and turmeric powder.

Bring the mixture to a boil.

Let it simmer for a few minutes until the flavors are well combined and the dal reaches the desired consistency.

Season with salt to taste, and then turn off the heat.