First off heat the oil in a bigger sized casserole dish (big enough for a whole lot of soup) and add the garlic, ginger, lemongrass, chillies, onion, spices and peppers and bring it to a sizzle. Sauté for a few minutes.
Then add the liquids – the stock and coconut milk.
Add the carrots, celery, potato, herbs and chicken. Ensure the liquid covers the veggies and the meat. Add more water if necessary.
Cook for about 40 – 50 minutes, stirring every now and then, until veggies feel soft and adding extra water if the liquid seem too little.
I like to break down some of the potatoes in my soup to thicken it up a little, but if you prefer your veggies intact, cook until soft, but not mashed.