Are you lost and confused because your recipe calls for Boiling or Boiler Onions?
As the name implies, boiling or boiler onions are used for boiling – primarily in recipes such as casseroles, cream dishes, soups, and stews.
Boiler Onions

They are small, white onions about an inch and a half round. They are mild in flavor and can be kept in a dry and well-ventilated area. When purchasing, make sure they are firm, with no spots, and are dry.
Substitutions:
Though different than a pearl onion, I have opted to substitute pearl onions when necessary. When using pearl onions, you’ll need to use twice the amount of pearl onions as they are about half the size of a boiling onion.

You can also substitute in equal measurements, yellow onions when needed. White onion could be used, but have a stronger taste.
You can also use shallots or cippolini onions if needed, but they would make the result of your soup a little different in flavor.
To cook a boiling onion, blanch in salted boiling water. Remove to an ice bath or place under cold running water. Drain and peel the onions.
Happy cooking! 💋