Split red lentils give this dal a mild, slightly nutty taste, and as the stew slowly simmers, they break down to a smooth consistency.
MELT 1 tablespoon oil in large saucepan over medium-high heat. ADD coriander, cumin, cinnamon, turmeric, cardamom, and pepper flakes; cook until fragrant, about 10 seconds.
STIR in onion, salt; COOK until softened, about 5 minutes.
STIR in garlic, ginger; COOK until fragrant, about 30 seconds.
STIR in water and lentils; BRING to a boil. REDUCE heat to low and simmer, uncovered, until lentils are tender and resemble coarse puree, 20 to 25 minutes.
STIR in tomatoes, cilantro, and remaining 2 tablespoons oil; SEASON with salt and pepper to taste. SERVE with lemon wedges.
Serve over rice or with pita bread.
You can't substitute other types of lentils for the rend lentils because they have a very different texture.