I don't know what this wedge-shaped item on my plate is, but it isn't a tomato, and a restaurant shouldn't call it such -- especially not in the middle of summer.
I haven't yet completed my visits to the restaurant in question, so you'll have to wait a couple of weeks to find out exactly where I ate -- or, rather, didn't eat -- this beaut. For now, I'll say only that, given the general quality of the restaurant, the presence of this "tomato" on my plate was especially disheartening.
(Sorry for the grainy picture quality. Had to resort to my phone after my camera battery died. The pale pink color came through clearly enough, though, I think.)