Place the malagueta peppers and salt in a mortar and crush them together with a pestle, or pulse to a thick paste in a food processor. Gradually add the onion and garlic and continue to mash or pulse into a paste. Add the lime juice to the paste and mash or pulse again until you have a liquid sauce. Cover with plastic wrap and allow to stand at room temperature for 30 minutes, then serve.
Preserved malagueta peppers are one of the hallmarks of Brazilian cooking. Extremely hot peppers are pickled in a 2:1 oil to grain alcohol ratio and allowed to rest for 1 month before using. They are available in some Latin American markets.
c.1997, M.S. Milliken & S. Feniger, all rights reserved