DELANO, Calif. — It is the obscurity of his father’s grave, not far from the once-tumultuous grape fields where farmworker history was made, that most troubles Johnny Itliong, a chef from Los Angeles.

“Larry deserves better,” Mr. Itliong said of his father, Larry Itliong, the fiercely determined, polyglot Filipino labor leader whose pivotal role in the farm labor movement continues to reside in history’s shadows.

Mr. Itliong, 47, looks much like his father did, though taller and ponytailed. Losing his father when he was 11, he grew up with a persistent longing, which has led him on a journey to bring his father’s accomplishments to light....