Rinse the red lentils under cold running water until the water runs clear. Finely chop the onion, dice the carrot, mince the garlic, and grate the ginger. Measure out spices and tomato paste.

Sauté aromatics

In a medium-large saucepan or Dutch oven, heat 1 tablespoon olive oil over medium heat. Add the chopped onion and a pinch of salt and sauté 5–7 minutes until translucent and beginning to brown at the edges. Add the carrot and cook 3–4 minutes until slightly softened. Stir in the minced garlic and grated ginger and cook 30–45 seconds until fragrant.

Toast spices & add tomato paste

Add the ground cumin, ground coriander, smoked paprika and turmeric to the pot and cook, stirring, about 30 seconds to bloom the spices. Stir in the tomato paste and cook 1 minute, scraping any browned bits from the bottom of the pan.

Simmer lentils

Add the rinsed red lentils and 4 cups water or vegetable stock to the pot. Increase heat to bring to a gentle boil, then reduce heat to low-medium to maintain a simmer. Partially cover and simmer 18–22 minutes, stirring occasionally, until lentils are very soft and breaking down.

Blend (optional) & finish

For a silky texture, use an immersion blender directly in the pot and pulse until smooth or leave slightly chunky by blending only 25–50% of the soup. If too thick, add up to 0.5 cup hot water or stock to reach desired consistency. Stir in lemon juice, chopped cilantro, 1.25 teaspoons salt (adjust to taste) and 0.5 teaspoon freshly ground black pepper. Warm through 1–2 minutes and adjust seasoning.

Coriander & Chilli Oil

Combine the oil, dried chilli flakes, ground cumin, smoked paprika and 0.25 teaspoon salt in a small heatproof bowl or jar. Warm the oil gently in a small saucepan over low heat until it just begins to shimmer and small bubbles form at the edge (do not let it smoke) — about 2–3 minutes. Alternatively, microwave in short bursts until warm (20–30 seconds) but not boiling.

Carefully pour the warm oil over the chilli and spices so they sizzle briefly and release aroma. Let the mixture cool 5 minutes, then stir in the finely chopped fresh coriander and optional citrus zest. Taste and adjust salt or chilli. The oil will infuse as it cools; store leftover oil in a sealed jar in the refrigerator for up to 1 week.

Garnish

Ladle the soup into bowls. Swirl 1–2 teaspoons of yogurt into each bowl if using, then spoon 1–2 teaspoons of the coriander & chilli oil over the top. Sprinkle extra chopped cilantro and toasted seeds. Serve hot with lemon wedges on the side.