Heat the olive oil in a large saucepan over medium-low heat. Add the onions, carrot and celery with a good pinch of salt and cook gently for 8–10 minutes, stirring occasionally, until softened but not coloured.
Add the garlic and cook for 30 seconds.
Add the ground coriander, cumin, cinnamon, paprika, ginger and Aleppo chilli flakes. Cook, stirring, for about 1 minute until fragrant.
Add the tomato paste and cook for another 1–2 minutes, stirring continuously. This helps deepen its flavour.
Add the red lentils, whole chilli, tomatoes, chickpeas and vegetable stock. Stir well and bring to the boil.
Reduce the heat and simmer gently, partially covered, for 10 minutes.
Add the rinsed quinoa and continue simmering for another 15–18 minutes, or until the quinoa and lentils are tender. Stir occasionally, particularly towards the end, as the lentils will begin to thicken the soup.
Remove the whole chilli. Add a little extra stock or water if you would like a looser consistency.
Season generously with sea salt and freshly cracked black pepper. Add the lemon juice gradually, tasting as you go. The lemon is important here — it should lift and brighten the spices without making the soup overtly sour.
Ladle into bowls and finish with a spoonful of yoghurt, a drizzle of extra virgin olive oil and plenty of fresh coriander. Scatter with a few finely chopped dates if using.
Omit the yoghurt, or use a plant-based yoghurt, to make the soup vegan.