Lou Seibert Pappas
By Lou Seibert Pappas
Roasting the onions before blending them with the broth gives French onion soup a caramelized flavor. You can prepare this soup, prior to adding the bread and cheese, up to 1 day in advance.
Preheat the oven to 375°F. Line 2 rimmed baking sheets with parchment paper.
In a large bowl, toss the onions with the oil and vinegar, then scatter the onions evenly in the prepared pan. Roast