"Contrary to one of the most popular of all misconceptions about kashrut, there is no such thing as a “kosher pickle.” Actually, all pickles are kosher because all fruits and vegetables are kosher. The pickles that are called “kosher pickles” are simply pickles that are cured in dill and garlic, and with seasonings that are popular among Jews of Russian or Polish descent. Since most American Jews come from Russian or eastern European backgrounds, and since they often eat this particular kind of pickle with their kosher meals, the pickle came to be known as a “kosher pickle.” It may be an especially delicious pickle, but it is not specifically kosher."
Answering the tough questions, Living Judaism, pp. 280 by Wayne D Dosick (via conversion-diary)