The flavoring for Massaman curry is called Massaman curry paste although ready-made pastes are now readily available but with all those artificial flavoring they are nothing in taste compared to homemade pastes prepared with fresh ingredients.

From the original site:

This Masaman Paste is much more spicier than other Thai Curry Pastes so do not add too much of it in curry, the quantity given below for Masaman Paste is sufficient to make curry twice and each will serve 3 – 4 people.

Get the Recipe: Homemade Thai Masaman Curry Paste