And Jacob was left alone, and a man wrestled with him until the break of dawn. When he saw that he could not prevail against him, he touched the socket of his hip, and the socket of Jacob's hip became dislocated as he wrestled with him…Therefore, the children of Israel may not eat the gid hanasheh, which is on the socket of the hip, until this day, for he touched the socket of Jacob's hip, in the gid hanasheh. (Genesis 32:25-33)
Why, in this case, do we remember something by not eating? In our tradition, we eat certain foods to remember events. On Passover we eat matzah to remember that we left in a hurry. On Chanukah we eat oily food and cheese to remember the miracles. So why do we not eat the gid hanasheh (as the sciatic nerve is called in Hebrew) to remember this event?
The Zohar describes Jacob's battle with the angel as an symbolic of man's struggle with his darker side. The entire night the battle remained even, as Jacob held strong.
As morning was approaching, the angel knew that he had to act fast, for soon the night—the time when he has power—would be gone, and he would be powerless. He therefore struck Jacob's thigh, the Zohar explains, in the place from which all sexual desire extends. And there, he was able to wound him.
The Zohar teaches us that in every struggle we are powerful and can overcome our evil urges if we so desire. There is only one place where the lust is so strong that even great men are powerless – the gid hanasheh. Its very name means to forget, because once it has been aroused, all rational thinking and religious scruples are left far behind.
The only way to win that war is to stay far away in the first place, for once the first flirt his been thrown out, there is no knowing where things can lead. For this reason the gid is not eaten at all but utterly avoided. (by Rabbi Menachem Posner)
