I am a big fan of curry, and salmon, so naturally... We are so blessed here in the PNW with the variety of seafood and freshness. We love to eat salmon as much as possible, and we usually try to aim for twice a week as per the US Dietary Guidelines for Americans.
Massaman curry paste is a mixture of different spices, lemongrass, peanuts, onions, and garlic - to name a few. Most of the ingredients are pretty common and easy to find, with the exception of lemongrass. If you can't find it, I think you could probably just leave it out and the recipe would still be delicious.