This is a Thai version of pickled Jalapenos/chillies known as 'Prik Nam Som', It is used as a condiment and can be served with most spicy dishes.
This recipe is easy & tastes just like the pickled chilies at Thai restaurants. The peppers really need to soak in the vinegar mixture for a minimum of 3 days for the flavor to develop. Or a week for my liking. I've made it a few times. It's foolproof! Thanks for sharing! - 06 Feb 2016 (Review from Allrecipes Southeast Asia)