Turkish Red Lentil Soup (Mercimek Çorbası)

Ingredients and substitutions

Choosing your ingredients

Buy split red lentils, sold in many stores as red lentils or masoor dal. They are hulled and split, so they soften in 15 to 25 minutes without soaking. Brown or green lentils keep their shape and give a grainy soup. Rinse the red ones in a fine strainer until the water runs mostly clear, which also cuts down the foam.

Pul biber is the Turkish name for crushed red pepper flakes. Wikipedia describes Aleppo pepper flakes as milder and oilier than ordinary crushed red pepper, with a slightly salty, fruity taste. Ordinary red pepper flakes work, but they are hotter and drier, so use half as much.

Keep the carrot and the paste in small amounts. Too much paste turns the soup sour and brick red, and too much carrot makes it taste like carrot soup. Chop both small, since they will be blended and only need to soften together.

Water is enough, and it lets the lentils, cumin and lemon taste clear. If you use broth, pick a low-salt one. Choose a pot of 3 to 4 quarts (3 to 4 liters), because the soup rises as it boils and a small pot boils over.

Possible substitutions

• Tomato paste: Turkish red pepper paste (biber salçası) for a deeper flavor. Taste first, because some brands are salty.
• Pul biber: Half the amount of regular red pepper flakes, or 1 teaspoon of sweet paprika with a tiny pinch of cayenne.
• Butter: Olive oil, for a dairy-free soup. Warm it the same way and the flakes will still color the oil.
• Lemon juice: White wine vinegar, starting with 2 teaspoons. Lemon tastes brighter, so use vinegar only if you have none.
• Dried mint: Dried oregano, or leave it out.

Step-by-step method

1. Prepare the lentils and vegetables. Rinse the lentils under cold water in a fine strainer for about a minute, stirring with your hand, until the water runs nearly clear. Drain well. Chop the onion and carrot into small, even pieces, about the size of a pea, and mince the garlic. Keep everything near the stove, since the next steps move quickly.
2. Soften the onion and carrot. Warm the olive oil in a heavy 3 to 4-quart (3 to 4 L) pot over medium heat. Add the onion, the carrot and a pinch of the salt. Cook for 8 to 10 minutes, stirring often, until the onion turns translucent and a piece of carrot gives easily when pressed with the spoon. Keep the color pale, because browning makes the soup taste roasted.
3. Toast the paste and spices. Add the garlic, tomato paste, cumin and paprika. Stir constantly for about 1 minute, until the paste darkens to a brick red, sticks slightly to the pot and smells toasted. Garlic and ground spices turn bitter if they scorch, so add a splash of water if the pot looks dry.
4. Simmer the lentils. Stir in the lentils and the water and bring to a boil over high heat. Skim off any pale foam. Lower the heat to a gentle simmer, partly cover and cook for 18 to 25 minutes, stirring now and then. The soup is ready when the lentils have collapsed into a cloudy orange liquid and mash easily against the side of the pot.
5. Blend until silky. Take the pot off the heat and let it sit for 5 minutes. Blend with an immersion blender for 1 to 2 minutes, until you see no grains or flecks of carrot. With a standard blender, work in batches that fill it less than half way, remove the lid's center cap and cover the opening with a folded towel, so hot steam can escape.
6. Adjust consistency, salt and lemon. Return the soup to low heat. Thin it with hot water, a quarter cup (60 ml) at a time, until it falls from a spoon in a smooth ribbon that settles in a couple of seconds. Stir in the remaining salt, the lemon juice and black pepper. Simmer for 2 to 3 minutes, then taste and add more salt or lemon in small amounts.
7. Make the pepper butter and serve. Melt the butter in a small pan over medium-low heat for 1 to 2 minutes, until it foams. Add the pul biber and dried mint and stir for 15 to 30 seconds, until the butter turns a deep red-orange and smells fragrant. Pull it off the heat before it smokes. Ladle the soup into bowls, spoon the butter on top and serve with lemon wedges and bread.

Storage and reheating

Refrigerate the soup within two hours of cooking, in shallow airtight containers so it chills faster. It keeps for 3 to 4 days in the refrigerator, or about 3 months in the freezer, with an inch (2.5 cm) of space at the top of the container. Make the pepper butter fresh when you serve.

The soup thickens a lot as it chills. Reheat it over medium heat with a splash of water, stirring often, and bring it to a full boil, or at least 165°F (74°C), before serving. Thaw frozen soup overnight in the refrigerator first. Taste again after reheating, since a little lemon lifts the flavor.

Common mistakes

• Skipping the rinse. Unrinsed lentils throw up more foam and can taste dusty. A minute under cold water is enough.
• Browning the onion. Dark onions give a roasted flavor that does not fit this soup. Keep the heat at medium.
• Salting everything at the start. The soup concentrates as it simmers, and the paste and lemon add their own sharpness. Add only a pinch at first and finish the seasoning after blending.
• Blending hot soup in a sealed blender. Steam expands fast and can blow the lid off. Vent the lid, fill the jar less than half way, or use an immersion blender.
• Leaving the soup too thick. A thick soup tastes heavy and pasty. Thin it with hot water until it pours easily, and expect it to tighten as it stands.