Toast belacan in a small pan until crumbly. This will take about 3 to 5 minutes. Remove and allow it to cool.
Remove seeds from chilies and cut into small pieces.
Transfer the chilies to a stone mortar. Pound with the pestle until the pieces are broken. Add toasted belacan and continue to pound until desired fineness. Alternatively, chilies and toasted belacan may be place in a food processor and processed until fine.
Squeeze in the lime juice and stir to mix. Transfer to a small dish.
If not consuming right away, transfer to a jar and store in the refrigerator. Squeeze in the lime juice just before serving. Best consumed within 2 to 3 days.