Silver blades of high-tensile carbon steel flash inside the kitchen of the inner city restaurant known as The Blackanese.
Sushi chef Themba Khumalo sharpens the blades, saying he feels naked without his treasured Japanese knives.
"If you don't have a knife, you don't have sushi," Khumalo said. "You have to sharpen your knives each and every morning when you come to work."
Khumalo is perfecting the art of fusion cooking, the delicate art of combining cultural and culinary traditions. The Johannesburg chef's unique mission is to 'Africanize' the Asian delicacy sushi, to get more black people to eat it.
In front of a pitch black wall decorated with golden chopsticks, Khumalo sculpts maki: teardrop-shaped mouthfuls of raw salmon, cucumber and avocado, surrounded by sticky, white rice, in a wrap of paper-thin dark green seaweed.
Khumalo is paid to create "sushi art," as he calls it, at The Blackanese - an eatery that's the brainchild of 30-year-old restaurateur Vusi Kunene.
Kunene was raised poor, in a village in Mpumalanga Province. On special days, he says, his family would eat chicken. But mostly, they could afford only porridge and spinach on his mother's meager income as a vegetable seller.
"I don't think there was sushi at that time in Africa," he said. "I never knew anything about sushi."
After his mother died, Kunene left school at 14 and moved to Johannesburg, surviving on odd jobs, eventually becoming a waiter in a sushi restaurant.
He became mesmerized by the process of crafting sushi and set out to learn as much about it as he could.
"At the time the chefs were Japanese, were Chinese, who could not speak English," he said. "And who were not willing to share the information. Then I started doing my own research, on the Internet and stuff like that, and moving to different types of sushi restaurants."
Kunene opened his restaurant two years ago with a mission to create sushi for the African palate.
"People tend to think sushi is raw fish, which it's not," he said. "Sushi's a combination of rice and vinegar. That's why you can actually have sushi without raw fish. Raw fish is just one of the fillings."
To "Africanize" sushi, Kunene's recipes include traditional South African ingredients such as springbok and kudu antelope and biltong, dried spiced meat.
"Now, immediately when you talk to an African person and then you're telling them about biltong sushi, I think they are willing to listen," Kunene said. "They are willing to try it out. And then immediately when they get into it, this is when you sort of push them into the extremes."
When The Blackanese opened, most of Kunene's customers were white. Now he says his clientele is 50 percent black.
At a table in the eatery, a young man dressed stylishly in a blue cashmere sweater, tucks into sushi rolls while working on his iPad.
He's Seth Mbhele, a digital strategist and one of Kunene's best customers. He recalls the first time he tasted sushi a few years ago.
"Tuna sashimi," Mbhele said. "Once you get over the idea of what it is that you're eating, it becomes enjoyable. I'm here pretty much four times a week, I think."
Kunene is thrilled to be changing South African eating habits by demystifying sushi and giving it an African spin.