Add the chilli flakes, vegetable stock, lime juice, garlic, salt, black pepper and coriander. Bring the mixture to a boil and then reduce down to a simmer. Simmer for about 5 minutes before adding the coconut milk, turmeric and lime zest then bring to simmer again for another 5 minutes or until the sauce thickens.
Optional
If you want the sauce to be a little thicker, mix 1 tablespoon of corn starch with 1 tablespoon of water and add into the sauce. You may need to raise the heat slightly to bring this to a boil to activate the corn starch.