Spring onions are those that have been harvested early-they look like scallions with large white bulbs. If they're unavailable, use Vidalia onions. Rotini (corkscrew pasta) will work in place of fusilli.
This version subs in mushrooms for the traditional beef without losing a lick of flavor. So savory and juicy after a good simmer, mushrooms are a natural for this dish.
The fresh salsa called for here has a natural low-sodium advantage over bottled commercial salsa, but if you don't want to make your own salsa, buy a container of fresh salsa from your grocery store deli section.
