Michael McCarthy had the accident at the Dalmunzie House Hotel in September 2000 during a busy spell in the kitchen, the Times of London reported Wednesday.
He had successfully cut 12 avocados, but the unlucky 13th was not ripe, and the 10-inch knife slashed the little finger of his left hand.
McCarthy claimed the cut, which was bandaged and later required suturing, destroyed his dream of becoming a Royal Air Force chef. He now works at an insurance call center.
He was off work for more than two months, losing $1,800 in wages, and had to give up his hobbies of skiing, cooking, motorcycling and mechanics temporarily.
Hotel owner Alex Winton said McCarthy was holding the fruit in his hand instead of against the cutting bench.
"There is no one in this hotel who has ever been allowed to cut soft fruit or avocado in that way," he said.