wild salmon with agridolce blueberries
sliced onion should work and maybe a tiny bit of garlic.
I'd go with chopped or thinly sliced red onion. The flavors are similar.
That was a great recipe from Melissa Clark in NYT this morning, wasn't it? Enjoy it! I also usually substitute red onion if I don't have shallot, and if I don't have red onion, I use white or yellow onion.
Scallions/green onions would work in a pinch, too.
The white part of Scallions or sweet onions