Carrot and Lentil Soup

Ingredients 2 tbsp olive oil 2 red onions, diced 2 celery sticks, diced 2 large carrots, peeled and diced 2 garlic cloves, finely chopped 30g/1oz fresh root ginger, peeled and finely chopped 1 tsp sea salt 15g/½oz fresh coriander (leaves and stalks), washed and finely chopped 1 tsp ground turmeric 1 tsp caraway seeds 1 tsp ground cardamom seeds 200g/7oz red lentils 225g/8oz baby spinach, washed salt and freshly ground black pepper To serve 4 tbsp plain yoghurt (or plant-based yoghurt) 1 lime, finely grated zest and juice