French onion soup may seem simple at first, but its success depends on using the right onions. To keep things classic, use yellow onions, which allow for the most nuanced flavor.

Slice your onions so that they are palpable within the broth and you get actual pieces in the soup. If they're chopped too small, they won't have any texture.

While it might be tempting to slice them parallel to the rings of the onion, it may be better to slice them from pole to pole to keep the slices more intact as they cook.

While the amount of time it takes onions to caramelize can vary, it's often recommended to do so over low heat for at least an hour, and potentially even two or three.

Before any onion hits the pan, make sure all the slices are separated out so that you'll be able to caramelize them evenly. Caramelize them in butter with salt and pepper.