Red Lentil And Chickpea Soup

• 1 red onion, diced
• 1 small knob of fresh ginger, finely chopped
• 3 saffron threads
• 1 tablespoon fresh turmeric, grated
• 1 tablespoon Harissa
• 1½ litres vegetable stock
• 1 cup chickpeas
• 1 cup red lentils
• 300 grams ripe tomatoes, chopped
• 1 medium carrot, diced
• 1 celery stick, diced
• 1 teaspoon cardamom, ground
• ½ teaspoon nutmeg
• ½ bunch fresh coriander, chopped
• 1 cup of plain yoghurt