In the best spy thrillers, rather than turn over a secret paper, the spy eats the secret. In 16th century Italy, the shrewd Italians literally ate the secret to one of the area’s most beautiful industries, the famous Venetian glassworks. To make crystal-clear glass, the Venetians used a plant that grows in salty soil, often along marshes and coastal areas. This plant was commonly eaten boiled, and tossed with olive oil and lemon juice. This plant not only tolerated the salty soil, but was the source of the glassworks’ secret ingredient, soda ash. So the Italians were literally eating their trade secret.

The plant, Salsola soda, or Agretti, is also known as Barba di Frate, Salsola Soda and Roscano. This Mediterranean annual sports long, green foliage that looks like very thin green onions. Even though agretti is very popular in Italy, it is virtually unknown in the United States. And that is a shame, because it is one of the best of the so-called bitter greens. It has a bit of the metallic sharpness of spinach, yet it’s more pleasingly bitter or sharp.