Harira with lamb

Ingredients

• 1 cup (200g) dried chickpeas (garbanzo beans)
• 20 grams (¾ ounce) butter
• 2 medium brown onions (300g), chopped finely
• 2 stalks celery (300g), trimmed, chopped finely
• 2 cloves garlic, crushed
• 4 centimetre (1½-inch) piece fresh ginger (20g), grated coarsely
• 1 teaspoon ground cinnamon
• 1/2 teaspoon ground black pepper
• pinch saffron threads
• 500 grams (1 pound) diced lamb
• 3 large tomatoes (660g), seeded, chopped coarsely
• 2 litres (8 cups) hot water
• 1/2 cup (100g) brown lentils
• 2 tablespoons plain (all-purpose) flour
• 1/2 cup (100g) cooked white long-grain rice
• 1/2 cup firmly packed fresh coriander leaves (cilantro)
• 2 tablespoons lemon juice