2 cups dried red lentils (we used oiled dal from an Indian grocery, which yielded a more traditional result, but red lentils are a fine substitute), soaked overnight in water to cover
3 cloves garlic, minced
1-inch knob ginger, peeled and minced
1 small onion, diced
1 small green chili, minced
1 1/2 tsp turmeric
1/2 tsp cayenne pepper
1 tsp coriander
1 Tbsp coarse salt
1 Tbsp brown sugar
juice of 1 lime
3 Tbsp prepared Mexican mole sauce (this ingredient, admittedly, is not traditional in India, but adds a nice depth if you've got it)
1 tomato, chopped
2 Tbsp high-heat oil, such as grapeseed or canola
1 tsp mustard seeds
1/2 tsp fenugreek seeds
1 large handful cilantro leaves, washed, dried and roughly chopped
Drain the dal and place in a large pot, and add water until it's covered to a depth of ~3 inches. Cover with a lid and bring to a boil, then reduce the heat until it's just high enough to maintain a healthy simmer. Simmer for ~30 minutes, until the dal is cooked and just barely beginning to break down. Add the garlic, ginger, onion, and chili, and simmer an additional 15 minutes.
After the dal has simmered, add the turmeric, cayenne, coriander, salt, sugar, lime juice, and mole (if using). Continue to simmer until the dal totally breaks down to form a smooth, soupy puree (it's pretty hard to overcook this — it will probably take another ~20 minutes to fully break down, but tacking an additional half hour on after that doesn't hurt). The dal will be fairly soupy, but if it's too thin for your liking, uncover for the last part of cooking until it reduces to a slightly thicker consistency. Taste to adjust seasonings, and add the chopped tomato.
When the dal is done to your liking, heat the oil over a high heat in a small saucepan with a lid. Add the mustard and fenugreek seeds, cover, and cook until the seeds pop. Dump the seeds and oil into the dal, and stir to combine. Remove from the heat, top with a sprinkling of fresh cilantro, and serve.