Workers at The Indian Tree in Portadown, Northern Ireland, were given the huge wedge by the loyal customer after he paid for a £79.05 meal.
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The businessman, who lives abroad and wishes to remain anonymous, has been a fan of the restaurant's chef since 2002 and enjoys a meal there every time he is home, belfastlive.co.uk reported.
He had been one of a family group of five when he pulled the chef aside to say thank you after his meal.
Restaurant director Luna Ekush said: "He has been a loyal customer of Babu (the chef) since 2002 and since he moved abroad, when he flies home into Belfast, he would call and see what Babu is cooking.
"He comes in then goes home, it's amazing that he is so happy with the food and service and environment here.
"That day he pulled Babu aside and said he would like to say thank you and that he had a small token. We just turned and were like, 'that's not small, are you crazy?'
"We were all in shock but he took the machine and typed it in, he paid on card, and then he said, 'now I would like to pay for my meal'.
"He said he wanted to stay anonymous but we could not stay quiet about this."
The Indian Tree has been open since September 2015 and Luna paid tribute to chef Babu for his loyal customers who follow him.
"Wherever he goes, the customers follow," she said. "He is very proud of it, he cannot believe it, it is such a big reward."