What condiments is known as marshworts?

"Marshworts" is not a known term for any condiment. It's possible there's a misunderstanding or a mishearing.

Could you perhaps provide more context?

* Did you hear it in a specific context? (e.g., a restaurant, a movie, a conversation)

* Was it written down? (e.g., a menu, a recipe)

* Do you remember any other details about it? (e.g., what it looked like, how it smelled)

With more information, I might be able to help you figure out what condiment you're thinking of.