• 3 tablespoons olive oil, more for drizzling
• 1 large onion, chopped
• 2 garlic cloves, minced
• 1 tablespoon tomato paste
• 1 teaspoon ground cumin
• ¼ teaspoon kosher salt, more to taste
• ¼ teaspoon ground black pepper
• Pinch of ground chile powder or cayenne, more to taste
• 1 quart chicken or vegetable broth
• 2 cups water
• 1 cup red lentils
• 1 large carrot, peeled and diced
• Juice of 1/2 lemon, more to taste
• 3 tablespoons chopped fresh cilantro

1. In a large pot, heat 3 tablespoons oil over high heat until hot and shimmering. Add onion and garlic, and sauté until golden, about 4 minutes.
2. Stir in tomato paste, cumin, salt, black pepper and chili powder or cayenne, and sauté for 2 minutes longer.
3. Add broth, 2 cups water, lentils and carrot. Bring to a simmer, then partially cover pot and turn heat to medium-low. Simmer until lentils are soft, about 30 minutes. Taste and add salt if necessary.
4. Using an immersion or regular blender or a food processor, purée half the soup. Soup should be somewhat chunky.
5. Reheat soup if necessary, then stir in lemon juice and cilantro.
6. Serve soup drizzled with good olive oil and dusted lightly with chili powder if desired.

Variations from comments:

1. I did add an extra 2 cloves of garlic, extra 1/4 c of lentils, an extra carrot, and used 1/4 tsp chili powder, 1/4 tsp cayenne, and 1/4 tsp of kebab spices ( mostly coriander and cumin)
2. add 1 teaspoon of curry powder to the spices and then serve the soup with a dollop of yogurt. I also saute the carrots with the onion and garlic to bring out more sweetness.
3. This is a wonderful soup with the following amendments: double the spicing, use three carrots instead of one, and use an entire small can of tomato paste. Salt to taste. I also add a dollop of plain yogurt on top at the end when served with the cilantro.
4. I followed the advice of others here and added a lot more spices: 1 extra TBS of tomato paste, 1 tsp smoked paprika, 1tsp smoked coriander, an additional tsp of salt. Also let it simmer an extra 10 minutes which thickened it up a bit.
5. Made some changes, some taken from the Cooks Illustrated version I just saw in my email. Used both cumin and coriander - both toasted and ground fresh. The coriander has some natural lemon essence. Added a pinch of cinnamon and also a squirt of harissa (and went easy on the chile powder). I also sautéed the carrots with the onion, but that was only because I goofed. Only change for next time - less liquid as others have also suggested. Maybe a bit more tomato paste too.

Serves: X      Total cook time: X
Source: NY Times Cooking - https://cooking.nytimes.com/recipes/1016062-red-lentil-soup-with-lemon