Wrap the cut onion tightly in plastic wrap or beeswax wrap
Place it in an airtight container or sealed zip-top bag
Store it in the refrigerator
Keep it away from strong-smelling foods if possible
Use it within 7 to 10 days
Store chopped onion in a separate sealed container
Label the container with the date if needed
Discard if it develops an off smell, slimy texture, or mold