I would say business casual. You can wear whatever you like but it is a nicer restaurant.
https://exploringyourmind.com/sawubona-african-tribe-greeting/amp/#referrer=https%3A%2F%2Fwww.google.com&_tf=From%20%251%24s
You will be welcomed in almost any attire, but I like to think of this place as being on the slightly more formal side.
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