1 cup skinned split brown lentils (salmon-colored in this form, masoor dal), picked over for stones
2 tablespoons canola oil
1 large green bell pepper, cut in half lengthwise, stem and seeds removed, finely chopped
2 to 4 fresh green Thai, cayenne, or serrano chiles, to taste, stems removed, thinly sliced crosswise (do not remove the seeds)
1 medium-size tomato, cored and cut into 1/2-inch pieces
1 1/2 teaspoons coarse kosher or sea salt
1/2 teaspoon ground turmeric
1/4 cup finely chopped fresh cilantro leaves and tender stems
Place the lentils in a medium-size saucepan. Fill the pan halfway with water and rinse the lentils by rubbing them between your fingertips. The water will become cloudy. Drain this water. Repeat three or four times, until the water remains relatively clear; drain. Now add 3 cups water and bring to a boil, uncovered, over medium heat. Skim off and discard any foam that forms on the surface. Reduce the heat to medium-low, cover the pan, and simmer, stirring occasionally, until the lentils are tender, 10 to 15 minutes.
While the lentils are cooking, heat the oil in a medium-size skillet over medium heat. Add the bell pepper and chiles, and cook, uncovered, stirring occasionally until the bell pepper initially releases its water and then starts to brown, and the hot chiles smell pungent (adequate ventilation will help clear the air), 10 to 12 minutes.
Stir in the tomato, salt, and turmeric, and scrape the bottom of the skillet to deglaze it, releasing the browned bits. Pour in 2 cups water and cook, uncovered, stirring occasionally, until the tomato has softened and turn slightly pulpy, 5 to 8 minutes.
Once the lentils are tender, pour the bell pepper sauce into the pan. Raise the meat to medium and continue to simmer the dal, uncovered, stirring occasionally, until the flavors mingle and the sauce thickens slightly, 5 to 8 minutes.
Stir in the cilantro, and serve.