Set a 10-inch non-stick skillet over medium-high heat.
Add the sliced onions, water, olive oil, and salt. Stir briefly and cover.
2b. Check on your onions to prevent burning to the bottom after 5 minutes.
Wait for the water to fully evaporate, which will take about 10 minutes.
Uncover the pan and press the onions firmly into the bottom and sides to create better contact.
Continue cooking the onions, stirring and pressing every 30 seconds, until they are completely browned, about 10 minutes.
Optional: Add a small amount of baking soda dissolved in water to boost sweetness.
Season with balsamic vinegar and extra salt to taste.
