Sambhar vada: yellow lentil soup with spiced doughnuts

INGREDIENTS

• 200g/7oz yellow lentils
• 1 onion
• 1 green chilli
• 2 tomatoes
• 1 tsp chilli powder
• ½ tsp turmeric
• salt
• 1 tbsp sunflower oil
• 1 tsp black mustard seeds
• 1 tsp cumin
• 2 fresh curry leaves
• 1 tbsp sambhar powder (available from Asian grocers)
• 4–5 tbsp tamarind
• 2 sprigs fresh coriander
• 200g/7oz black gram (urid or urad) lentils, soaked in water for 1 hour
• 1 tbsp rice
• pinch bicarbonate of soda
• 450ml/16fl oz sunflower oil