"Gourmet" I remember there was a fake lettuce plot in it.

It is a French film released in 1976, directed by Claude Zidi, starring Louis de Finèce, Coluche and others.

"Gourmet" tells the story of Charles Duchemin (Louis de Funès), the editor-in-chief of a food magazine, who has a gifted sense of smell and taste. He can tell whether the food is as delicious as the legend says by smelling it with his nose and tasting it with his mouth.

In order to let readers taste truly delicious food, he often disguises himself and sneaks into major restaurants and hotels to taste the food. If the food is good, he will highly recommend it in the magazine, and if the food is bad, he will scold it.