Heat the oil in a large saucepan over medium-high heat. Add the onion, celery, garlic and broccoli with a good pinch of salt and cook, stirring, for 5 mins or until vegetables soften then add the lemon zest and stir through.
Add the stock and stir to combine then cover with a lid and cook for 10 mins or until the vegetables are tender, adding the peas and spinach, stir through and remove from the heat.
Carefully blend the soup until smooth and adjust the seasoning to taste.
To serve, ladle the soup into serving bowls. Drizzle with a little olive oil, spoon over the yoghurt and sprinkle with the coriander and chilli.