For the Coriander Stock
In 1 litre of water, make a stock with the stems of chopped coriander, onion, celery and 2-3 cloves of chopped garlic. Boil the stock for 7-10 minutes. Strain the stock and keep aside.
For the Soup
Take some chopped garlic and whole peppercorns in a pan. Sauté for a while. Now, add the stock. Add salt, pepper, lemon grass, kaffir lime leaves and let it cook for another 5-7 minutes. Before serving, remove the lemon grass and kaffir lime leaves. Add finely chopped coriander leaves, zucchini noodles, spring onions and lemon juice and serve hot.