Order cơm cháy with goat sauce, the pairing the dish was actually built around
Fried when you order, not before
Cơm cháy is a sheet of rice crust, cooked in a thick cast-iron pot over wood, dried, stored, then deep-fried to order. It is credited to Đinh Hoàng Thăng, a young man who adapted what he had learned working in a Chinese-run kitchen during the colonial period, roughly 120 years ago. Goat and cơm cháy houses serve it across Ninh Bình city and Hoa Lư ward; the largest of the new generation, run by Vũ Trí Thức, born 1991, in Hoa Lư ward, gets through around 20 goats and 300 covers a day at peak.
Why it's unique
The packaged snack version is now sold the length of Vietnam, which is exactly the reason to eat the fried-to-order version at source. This is a named local invention of roughly 120 years' standing, not a generic crisped rice, and the canonical way to eat it is with sốt dê, a sauce made from Ninh Bình mountain goat.
The making is specific. The rice is a blend rather than one grain, tám thơm from Hải Hậu mixed with a drier rice, which is what makes the sheet puff rather than shatter. It is cooked in a thick cast-iron pot over wood, the loose rice is lifted out, and the crust is left to colour until it releases itself from the base. Only then is it dried and stored, and the frying happens when you order. That last step is the whole difference between this and the bag.
Before you go
Ask for it with sốt dê, the goat sauce. Ruốc, pork floss, and spring onion oil are the simpler home versions, and they are what you get by default in some places. If the sheet arrives already soft, it was fried too early.
Avoid ordering it as a takeaway box at a viewpoint restaurant, which is the factory product with a view attached. Lunch and dinner. Mid-range by Vietnamese standards, because the goat dishes carry the bill. Book, or expect a wait of about half an hour, on public holidays and especially over 30 April and 1 May. Cash is widely preferred.