AdiKempler posted a short video to herTikTokaccount describing the easy process.
First squeeze a few pumps of dish soap into the stained Tupperware.
Then add warm water until the container is about half full.

Place a few pieces of torn-up paper towel into the water, and seal the Tupperware lid closed.
Next, shake the Tupperware vigorously for 45 seconds to one minute.
Remove the paper towel pieces, rinse out the soapy water and enjoy your freshly cleaned and stain-free Tupperware!

But was it sleight of hand?
Coat the stained Tupperware with the paste and let it rest for 15 minutes.
Scrub and rinse it out.
To avoid stains, wait until the sauce is cool, or store it in aglass containeror jar.