Onscreen, Mr. Smith was a bubbly presence in a striped apron, an ordained Methodist minister, a husband and father who waxed sentimental about family cooking traditions. He traveled with camera crews to China and Greece, encouraged viewers to cook from immigrant traditions, and made food interesting and approachable. His cooking mantras — “hot pan, cold oil, food won’t stick” “keep your fingers bent under” — are still invoked by Americans who grew up watching him.