She said she went back to the store to ask for a refund.
Richardson said that is when a worker got the manager, who came out, cursed at her, and threw the sandwich at her head.
A viral video of the incident has more than 2 million views.
Richardson said she doesn't want anybody to be treated like that.
"He doesn't get to treat anybody like that and that they get somebody into Subway to treat people with respect and fix problems when you're wrong. That's what you're supposed to do," Richardson said.
Richardson is now suing the franchisee of the store for $25,000 for physical and emotional harm.
In a statement, her lawyer said the conduct was "disgraceful and deplorable, and should greatly concern everyone who eats at Subway and expects Subway stores and their owners to provide a safe, family-friendly environment, free of sexist discrimination and violence."
A Subway spokesperson said the franchise owner regrets how he handled the situation, saying, "The local team has reached out to the guest to apologize on behalf of the restaurant as this incident is inconsistent with the high standards Subway requires of its franchise owners."
Richardson's lawyer said the company did not reach out to Richardson directly.
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