Kroepoek, for lack of a better description, is the Dutch word that refers to a few different kinds of deep fried rice crackers served as a side dish with spicy Indonesian food. The two kinds of kroepoek I am familiar with are:
- kroepoek oedang (my favorite), made with rice flour, shrimp and pinkish-colored as a result
- kroepoek palembang, which is made with rice flour and fish, and usually pale golden brown in color
Although I realize neither of those may sound particularly tasty, I promise they're a nice complement to the scorch of sambal. You can buy kroepoek dried (in which case you have to deep fry it yourself) or pre-fried, in the Asian foods section of any Dutch supermarket. It's considerably harder to find in the States, but you might try Asian grocery stores.
If you read Dutch, a nice description of the different kinds of kroepoek can be found at:
http://www.xs4all.nl/~rjmmilt/info/inf00950.htm