In a large pot, heat olive oil and sauté chopped onion and crushed garlic until softened.

Add soaked chickpeas, white beans, green lentils, pearl barley, grated carrot, grated celery root, and chopped celery. Stir to combine.

Add 10 cups of water, turmeric, salt, and black pepper. Bring to a boil.

Reduce heat to a simmer and cook for about 120 minutes until the legumes and barley are tender.

Squeeze the juice of one large lemon into the soup before serving, and stir well.

Serve hot, topped with fresh coriander.