Prep the base: Heat the olive oil or butter in a large pot over medium heat.
Add the chopped onion and a pinch of salt. Cook 3–4 minutes until softened and fragrant.
Add vegetables: Stir in the carrot and potato. Cook another 3–4 minutes, stirring occasionally, until they begin to soften.
Bloom the spices: Add the tomato paste, cumin, paprika, and turmeric (if using).
Cook for 1 minute, stirring, until the paste darkens slightly and smells toasty. This step builds flavor.
Add lentils and liquid: Stir in the rinsed red lentils. Pour in the broth and bring to a gentle boil.
Reduce heat to a simmer.
Simmer: Cover partially and simmer 20–25 minutes, until the lentils are very soft and the vegetables are tender. Skim any foam if needed.
Blend to your preferred texture: For a classic silky soup, use an immersion blender to purée until smooth. For a rustic version, mash lightly with a spoon or blend only half.
Add more broth if it’s too thick.
Season: Taste and add salt, black pepper, and Aleppo pepper if you like heat. Simmer 2 more minutes to meld the flavors.
Optional finishing drizzle: In a small pan, melt 1 tablespoon butter. Stir in 1/2 teaspoon paprika and a pinch of Aleppo pepper for 10–15 seconds.
Drizzle over each bowl.
Serve: Ladle into bowls. Squeeze fresh lemon over the top and sprinkle with dried mint or parsley. Serve with warm bread.