I learned how to make this from my Chinese in-laws. The "la" or "la-zhao" is actually the "la" of la-yu or ra-yu (hot chili sesame oil).

Ideally the oil should foam up and you should hear a sizzling sound when you pour the oil over the chili peppers. Mix rapidly or the chili peppers will burn and blacken. Don't put your face too near the bowl when you are mixing up the chili peppers, or the fumes will make you regret it! If you add extra oil, you can make ra-yu at the same time. Recipe by kou2091