I love haricot verts and shallots. Either sautéed together or crisp up the shallots on top.

Are they raw or cooked in the recipe?

Cooked -- I'd use sauteed regular onion.
Raw -- I'd add a little sauteed garlic to the recipe for the onion-y flavor, and also some slivered almonds for a textural/visual contrast with the beans.

I’ve seen spring onions sold at MOM’s and they have greens but are more bulbous than scallions. I’d try to sub sweet onions.

Anonymous wrote:Scallions and spring onions are the same thing. Leeks or shallots would work too.

OP here. Not according to this: https://www.bonappetit.com/story/are-scallions-and-green-onions-the-same-thing#:~:text=In%20terms%20of%20flavor%2C%20scallions,stand%2Din%20for%20sweet%20onions

I'd use scallions.

https://www.thekitchn.com/whats-the-difference-between-spring-onions-scallions-and-green-onions-word-of-mouth-217111

Scallions and spring onions are the same thing. Leeks or shallots would work too.

I'm making an herb-roasted pork loin (Sunday Suppers) and the side attached to the recipe is spring onions and haricot verts (with sage and thyme). I have the beans in hand but it's not season for the onion. Looked online and found wildly varying suggestions for substitutes--consensus from posts seems to be no onion or shallot (too strong) but perhaps celery (? one of the recommendations) or leeks or scallions?