Try this homemade Onion Sandwich Au Gratin recipe the whole family will love. Made with onions, cold water, boiling water and bread. Easy step-by-step i…
This Onion Sandwich Au Gratin relies on simple, everyday ingredients such as onions, sliced, cold water, boiling water and bread, toasted. It comes together quickly and makes 4 servings, at about 187 kcal each. The step-by-step instructions below are written to be easy to follow, even on a busy day.
It's versatile enough for an easy weeknight dinner yet satisfying enough for guests at the weekend. Serve it with your favorite sides, and keep any leftovers for a quick meal the next day.
Updated Jun 30, 2026