Soak fresh chickpeas in a bowl of water for approx. 12-24 hours before preparing them. Then pour off the water and rinse the chickpeas again under running, clear water.
Pre-cooked canned chickpeas can be used immediately.
Peel the potatoes and cut into quarters.
Finely chop the garlic clove and fry in a little oil in a large saucepan. Add the potatoes and fry them briefly. Then add about 1 liter of salted water and cook the potatoes and chickpeas until the liquid is significantly reduced. Finely puree the potatoes and chickpeas with a hand blender. Add the lemon juice and season the soup with salt, pepper and cumin. Let the soup steep for another 20 minutes over low heat.
To serve, pluck the coriander and sprinkle it over the soup.