I put mine in the dishwasher. Always gets rid of the odor.

contrary to what seems to be popular belief, baking soda does nothing to get rid of or absorb odors.
Wash it well....the dishwasher will do a good job but you might want to shut off heated dry so the lid doesn't warp.

Thanks Eileen, I will try that. If that doesn't work I will try CindyMac and Linda92's suggestion of using the DW and shutting off heat dry. I am scared of warping.

Maybe you can find something to store in it to replace the odor. Maybe it will be a favorable one. (:

I would try soaping it up, really lathery, and leaving it overnight, and then rinsing.

Somehow I recall sunlight being a good factor in odor control. Maybe try leaving it out side in a sunny location for a day or two. Not sure where I heard that, probably on a camping trip or somewhere.

I always put my Tupperware in the dishwasher, lids I put on the top rack in the slots like plates. If I put it against the front of the rack, it keeps it from warping when I mess up and forget the "heated dry" is on.

Annie

The leftover container lid is made from a polymer. Strong odors will tend to adhere to it.

Two things can help to remove the odor:

1. After washing and drying it, cover it with a coating of vegetable oil & leave it on for a while (you can put inside a baggy or wrap). After a day or so remove the wrap, wipe off the oil and wash in hot soapy water.

2. A better way is this. After washing and drying, place the item in bright sun for a few days. I set on an outside table or suspect in the bright sunlight outdoors. However, bright sunlight will also work indoors I you have a place that gets a lot of sunshine. Give it a few days, food cut side up. You may want to do both sides.

Store crushed garlic in it. You will no longer have the Onion odor.