Wash the lentils thoroughly till the water runs clear, drain any excess water, and add to a medium-sized pot.
Add fresh water and place the pot over medium-high heat. Add salt, turmeric powder, and red chili powder. Stir to incorporate the spices, and bring the lentils to a boil, uncovered.Once there's a rolling boil, remove any scum that rises to the top and lower the heat to medium-low.
Cover the pot and let it cook for 15 minutes. When ready, the daal will have softened and can easily be mashed with the back of a spoon. Alternatively, use an immersion blender to achieve a smoother consistency.
Add more water to reach your desired consistency. About 1/4 cup more. Taste the daal and adjust the salt as needed. I usually add about 1/2 teaspoon more salt. Stir and switch off the heat.
For the tadka
Place a small pan on medium-high heat, add oil, and let it heat up. Once the oil shimmers, add the whole cumin, dried red chilies, and curry leaves.
Stir until well coated, then sauté for about 30 seconds. Next, add the sliced garlic and sauté for another 30-60 seconds, until golden brown.
Pour the whole concoction into the pot of cooked lentils, cover, and let the dal simmer for about 2 minutes to infuse with the oil.
Once ready to eat, stir the daal well to combine everything and optionally garnish with chopped cilantro and a squeeze of lime juice.