The Spurs manager revealed in the accompanying caption to the post on Instagram that he bought the leg of jamon Iberico around $650 in order to honour a promise to his left-back.
"A promise is a promise," Mourinho wrote. "It cost me £500 but I keep my promises."
According to Spanish newspaper ABC, Mourinho gave Reguilon some extra motivation in the build-up to Tottenham's Premier League match against Manchester City on Saturday, promising the Spain international the best leg of pork on the market of he could stop Riyad Mahrez dribbling past him during the match. Reguilon, 23, did exactly that by winning all four of his one-on-one duels against the City winger.
Not only did he help secure a 2-0 victory that sent his side to the top of the Premier League table, he also secured himself a prime cut of meat into the bargain, all bought and paid for by his coach.
However, Reguilon's teammate Erik Lamela raised questions about his technique when cutting the ham, which is traditionally savoured in wafer-thin slices.
You can't argue Mourinho's incentivised approach, but at this rate the remainder of the season is going to end up costing him thousands of pounds in butcher's fees alone.
Mourinho isn't the first Spurs boss to use food as a motivational aid, with his predecessor Mauricio Pochettino once preparing his entire squad for a local derby against West Ham United with a trip to a top Argentine steak house in 2017.
Some 50 members of the squad, coaching staff and even chairman Daniel Levy went out for a steak dinner at London surf and turf eatery Beast in the name of team bonding, with Poch footing the bill.
"When I pay, I pay good! Good restaurant, good food, good wine," he said afterwards. "[The choice was to] train tactically in the morning or to go out together at night to a restaurant. This is tactics, too!"
Spurs subsequently went on to win 3-2 at the London Stadium, and that was despite having a man sent off in the 70th minute.
Claudio Ranieri used pizza as a key motivational tool during Leicester City's incredible run to the Premier League title in 2015-16.
After conceding at least one goal in the first 11 games of the season, the Italian coach promised to buy pizzas for his squad if they successfully managed to keep a clean sheet.
A 1-0 win over Crystal Palace in October saw the Foxes fulfill their end of the bargain, with Ranieri duly honouring his later that same month.
"Champagne and pizza is good, not fantastic, but it's OK," Ranieri is quoted as saying after taking his team out for dinner.
"It's carbohydrate, good for the muscles. I'm very happy, very glad."
Many managers over the years have attempted to stamp their authority at a new club by banning certain foods and drinks from the canteen (who can forget Paolo Di Canio with his ice cubes?).
Condiments are usually among the first items to be forbidden, but England manager Roy Hodgson bucked the trend while he was England manager in 2014.
In the build-up to that summer's World Cup in Brazil, Hodgson reversed previous coach Fabio Capello's strict forbiddance of tomato ketchup and brown sauce -- a decision that proved immediately popular with his players.
England were eliminated from their group without winning a single match.