Is expiation obligatory upon one who swore not to eat grilled tomatoes, then ate them fried?

The validity of an oath depends on the intention of the swearer; for intention specifies a general لفظ (wording) and restricts an absolute one. So, whoever intends by his oath something that the wording can bear, his oath relates to what he intended, not merely what he uttered; due to the saying of the Prophet, peace be upon him: "And indeed, every person shall have what he intended." Thus, if he swears to eat meat or drink water, and by his oath he intends a specific item, his oath relates to that specific item and nothing else.