Xnipec

Xnipec is a spicy sauce native to the Yucatán peninsula, made with habanero pepper, purple onion, bitter orange juice and salt. Sometimes oregano, vinegar, bay leaf, coriander or pepper are also used. If sweet orange is used, lemon juice can be added to acidify it; if sour orange is used, it is not necessary. It is also called in a generic way Yucatecan sauce (salsa yucateca) or pickled onions (cebollas encurtidas). Since the Mayan-Spanish transliteration is not standardized, the ways of writing are various; other common spellings are ixnipec, xnepec, xni'pek, ni'peek, x-ni-pec, xnepek, etc., where peek means 'dog' and ni means 'nose'. It is similar to another very popular sauce in Mexico, pico de gallo, and it is common in the peninsular cuisine, where it is used regularly to accompany various typical dishes, including chocolomo, salpicón, poc chuc, and tikin xic. It is the traditional accompaniment to cochinita pibil, as well as panuchos.

Source: Wikipedia