Cook, stirring occasionally (every few minutes), until onions begin to shrink and have reduced in volume some.
½ cup water, dry white wine, or chicken broth
Once onions are softened and reduced in volume, reduce heat to medium-low and continue to cook, stirring occasionally/as needed, until onions are deep golden brown in color and caramelized. If the onions begin to stick or burn to the pan, simply deglaze with a splash of broth, water, or wine.
Use as desired.
Notes
Yield
The onions will shrink considerably as they cook. I find I need 2.5-3 lbs of onions for 1 cup of caramelized onions.
Storing
Store in an airtight container in the refrigerator for up to a week. They may also be frozen for several months.