No matter how you like to make your French onion soup, it's a simple fact that a certain type of onion is best for the job: the accessible, hardworking, regular yellow onion.

Though other varieties will work, most agree that this imparts French onion soup with the ideal sweet and savory flavor that's not too overpowering or too weak.

Yellow onions are also heartier with a higher starch content, allowing them to withstand the hours of cooking that are required for French onion soup.

The most important step in making French onion soup is perfectly caramelizing the yellow onions. A perfectly golden dark color will give the broth a strong and sweet flavor.