If you mix sautéed onions into a canned version of French onion soup, it will be infused with a deliciously strong onion flavor, and your soup will gain a delightful richness.
To sauté onions for your canned soup, grab a large skillet and place it on your stovetop over medium-high heat. Pour olive oil into the pan, then add butter and let it melt.
While the butter melts in the pan, thinly slice a few onions. After the butter has melted, spread the onions in the pan and season them with sugar and a bit of salt.