The roa is a smoked ballyhoo, fish that is native of Manado. The prominent smokey flavour of the fish makes this more than just an ordinary sambal especially with a squeeze of calamansi.
The roa is a meaty fish. You can always replace the it with any other smoked fish as long as it has enough meat to it.
Calamansi can also be replaced with lime or lemon.
If you prefer the sambal to be even spicier, just add the bird's eye chilies to your liking.