I think you'll find these in just about any Thai restaurant here, rather than from a single provider food-cart. So any street-based restaurant, or open-air restaurant will have these. They are usually dosed with a bit of "flavor enhancer" and finely ground white pepper, so they taste quite good. Beware though, they are super (temperature) hot, so let them cool for a few minutes. Many places serve these with a smooth (red-ish orange) chili sauce on the side. These same small portioned spare-ribs get made into a great clear soup which is sweet/sour/spicy.