In a fine mesh strainer, rinse 1 cup split red lentils with water a few times to remove any dirt or debris. Drain the lentils and transfer to a medium (3-quart) stock pot with 3 cups water.
Set the stock pot over high heat and bring to a boil. Using a spoon, skim off any of the white foam that comes to the surface.
Stir in ½ teaspoon ground turmeric. Reduce the heat to medium-low and simmer for 15 - 25 minutes, or until the lentils are extremely tender and have disintegrated into a somewhat mushy, soupy consistency but still retain some texture. Note: If you notice the water has reduced too much, you can add up to an additional ½ cup to ¾ cup of water until it's reached your desired consistency.
Meanwhile, set a saute pan with 1 tablespoon canola oil over medium heat. Add in 1 teaspoon cumin seeds and saute until they begin to sizzle.
Immediately add 1 large red onion, finely diced, and saute for about 8 - 10 minutes until onions are soft, translucent in the middle, and lightly browned on the edges. Note: You're looking for a golden brown color here, not burnt onions.
Add 2 garlic cloves, finely minced, and 1 serrano chili, and saute for 1 minute until aromatic.
Stir in 1 plum or roma tomato, diced. Simmer until the tomatoes break down and the tomato-onion mixture resembles a thick, almost paste-like consistency, 7 - 8 minutes.
Add 1 teaspoon garam masala, 1 teaspoon ground coriander, and ½ teaspoon kashmiri chili powder (if using). Season to taste with Salt and black pepper. Note: At this point, the mixture should taste slightly saltier and full of spice than you'd like it. Once you add the lentils, the flavor will be diluted, so feel free to adjust as necessary if you want more spice or salt.
Once the lentils are cooked, add them to the saute pan and stir, simmering for 1 minute. Season again with salt, pepper, or other spices if necessary.
Make the Crispy Garlic Tadka:
While the lentils simmer with the aromatics, set a small pan with 1 tablespoon canola oil over medium heat.
Add 1 large garlic clove, thinly sliced, and let sizzle until they just begin to turn a pale golden brown color on one side. Flip the garlic and cook on the other side until both sides are pale golden, about 2 minutes.
Add 1 teaspoon brown or black mustard seeds (if using). Once the seeds sizzle and pop, about 10 to 15 seconds, immediately take the tadka off the heat and pour over the dal.
Finish the Dish:
Garnish with 1 handful fresh cilantro and a squeeze of lime. Divide amongst serving bowls and serve immediately with rice or chapati.
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Notes
Before proceeding with the recipe, ensure your spices are fresh and aromatic, as older or stale spices may require increased quantities for optimal flavor.
Lentils are incredibly bland on their own, so you will want to be generous with the salt!
To keep the garlic crispy, pour the tadka on top of the dal just before serving. Even better, serve your dal in individual bowls and pour the hot tadka on top of the serving bowls.
Storage: Store leftover dal in an airtight container in the fridge for 4 - 5 days. To reheat, simply transfer it to a stock pot and bring to a gentle simmer until warmed through. While the garlic tadka won't stay crispy, the lentils keep really well for a few days.
Note: The nutrition facts does not include rice or chapati.