A sweet and perfectly caramelized balsamic onions dish perfect for serving on sandwiches, burgers, steak, or pork tenderloin! With a little patience and time, these onions are easy to make!
Add olive oil to a large saucepan over medium heat. Once shimmering, add your sliced onions, salt, and pepper. Stir well. Sauté for 8-10 minutes until the onions are translucent and begin to soften. If they start to fry or become golden, lower the heat to medium-low.
Stir in the balsamic vinegar and sugar. If you haven't already lowered the heat to medium-low, lower it now. Stir the vinegar into the onions well. Sauté for 35-40 minutes, stirring often. The onions need a lot of time to slowly release all of their liquid.
Let the onions and vinegar simmer very low for the entire time, making sure to stir so that the onions and vinegar don't begin to burn or stick. Remove from the heat and serve.
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Notes
Be patient. True caramelized onions take time. Anyone who tells you about "quick" caramelized onions is actually describing fried or sauteed onions.
Use the high-quality balsamic vinegar. Better balsamic is thicker and less watery. This is exactly what you want when you're cooking the moisture out of onions, not adding more in.
Control sticking or burning. If the onions or balsamic vinegar start burning or sticking to the pan, add a tablespoon of water, stir it well, and lower the temperature. The water will lower the temperature of the pan and loosen the sugars.