They’re all variations on the same theme - mustard and green chillies.
My friend’s mom’s 60s-era (grad school days) simplification:
Make a paste of Coleman’s mustard, salt, and olive oil
Coat salmon with the paste
Place sliced chillies (indian or thai or serrano - no jalapeño) on top
Cover tightly with foil and bake till just done - at 400F it’s probably 10-12 mins, at 300F it took me 20-25.
Squeeze of lime, eat with rice
There are more complicated versions (ie the originals) that start with soaked mustard seeds and include poppy seeds or coconut in the paste.
You can also steam this stovetop or en papillote (again, originals), but we all just make this version because it’s so easy and so delicious.
MJ’s version is a more complicated simplification, if that makes sense 
ETA: I’m going to try one of the original recipes. Will report back.
