Red lentil, chickpea & chilli soup

Ingredients

• 2 tsp cumin seeds
• large pinch chilli flakes
• 1 tbsp olive oil
• 1 red onion, chopped
• 140g red split lentils
• 850ml vegetable stock or water
• 400g can tomatoes, whole or chopped
• 200g carton chickpeas or ½ a can, rinsed and drained (freeze leftovers)
• small bunch coriander, roughly chopped (save a few leaves, to serve)
• 4 tbsp 0% Greek yogurt, to serve