It is said that there are two things most Greek cooks do not go anywhere without: a knife and an icon of St. Euphrosynos. For Orthodox Christians, St. Euphrosynos the Cook is the patron saint of cooks and chefs. This being the case, it is traditional for Orthodox Christians to have in their kitchens an icon of St. Euphrosynos. Those unaware of St. Euphrosynos typically follow the western practice of hanging a Leonardo DaVinci inspired "Last Supper" icon. For Orthodox, however, the depiction of the "Last Supper" is more appropriately called the "Mystical Supper", since it was primarily a liturgical event which is often reserved for depiction in the Holy Altar area of a church.
The life of St. Euphrosynos, who is commemorated every year on September 11th, can be read here, and at the bottom of this link is a prayer to St. Euphrosynos traditionally said before cooking.
Chef's Hats and Orthodox Monastics
It is worth noting, since St. Euphrosynos was an Orthodox monastic on Mount Athos, that tall white chef hats (toque blanche), according to many, have their origins in the black tall hats (kalimavkion) of Greek Orthodox monastics. It is said that in the middle ages, Greek monks who prepared food in the monasteries wore tall white hats so that they could be distinguished from the normal monks who wore tall black hats.