I enjoy watching the look of disbelief on people's faces when I tell them that I eat sweetbreads and then proceed to explain what they are. After all, their euphemistic name belies the fact that they are neither sweet nor breadlike. Sweetbreads are either the thymus gland or the pancreas of veal or lamb. For the cognoscente, they are highly prized for their mild flavor and velvety texture. You'll find none finer than at Tony Ruppe's (3939 Montrose, 713-852-0852). Two large slices of sweetbreads are perched aside a mountain of field greens ($8.75 -- alas, dinner only). Their irregular shape and milky white color are unmistakable; their texture is so tender that only a fork is required. The sweetbreads are first poached in a court bouillon, which imparts a mild flavor, then lightly drenched in flour and fried. Simplicity at its best.