Beluga Lentil "Caviar" on Potato Blini.
(Photo by Deb Lindsey for The Washington Post)How old are lentils? Here’s one clue: People who say lentils are shaped like lenses have the reference backwards. Turns out that the world’s first lenses got that name because they were shaped, yes, like lentils. The lentils came first. Way first.

Lentils are Pompeii old. Ezekiel old. Ancient Sumeria old. Stone Age old.

Before there were virtually any other legumes, there were lentils, offering up protein...