Now in her 80s, Kennedy is a cook's cook who was decorated with the Order of the Aztec Eagle, the highest honour given to foreigners in Mexico, for her work travelling around the country garnering recipes and cataloguing them in her cookbooks.
In her adobe house near the western city of Zitacuaro where she once fed Prince Charles, she savours everything from Mexican flying ants and rich pumpkin seed sauces to stodgy British pork pies and Stilton cheese with a good port.
She bemoans cooking trends that place more emphasis on how a dish looks than how it tastes and says culinary schools should hold classes for diners to teach people how to taste.
"We are forgetting that food should taste good, not only look good, but it should taste good first," Kennedy said at her ecologically friendly home.
Born in Essex in southern England, Kennedy says her mother was a great cook and despite the household having little money, she remembers a childhood with a varied and tasty diet.
A lifetime of recipes later, Prince Charles ate lunch at her home in 2001 and Queen Elizabeth awarded her the MBE (Member of the British Empire) medal for furthering British-Mexican relations.
Kennedy ended up in Mexico after meeting her future husband Paul Kennedy, a Mexico-based New York Times correspondent, on the steps of a hotel in Haiti. They fell in love, and she joined him in 1957.
"And then my life began," said Kennedy, a self-confessed eccentric.
Foie gras in the freezer
Widowed a decade later, Kennedy has travelled all over Mexico, a camp bed tossed in the back of her truck, to jot down unwritten recipes passed down by mothers and grandmothers.
Her first book The Cuisines of Mexico was published in 1972 and still sells today. Half a dozen followed and Kennedy is now in demand to give cooking demos in the United States.
Her next book will cover food from Oaxaca, a poor southern state where locals get their protein from fresh dragonflies, grilled grasshoppers and dried worms ground into sauces.
"I never make a lot of money because I have not written the low-cal, microwave Mexican cook book and I refuse to write it, I'd rather die," said Kennedy, admitting she is a snob about everything from food to clothes.
"I live in some ways modestly, but there is always foie gras in the freezer and a little bit of Champagne around just in case," she said.