Yes, vegetables with roasted lamb are usually roasted with the lamb.

[Did this guy know nothing of food? Now he was making suggestions. Not even the house elves did that when a meal was already ordered.]

I don't fancy picking my lamb off of a stick only for it to be overcooked. No, the way I mentioned is just fine. Surely you can't be the only cook here. Ask one of the others.

[Must she tell him step by step how to find out how to cook the meal she ordered? It would have been much easier if he just knew how to make it already. This was why new elves were given training before they were relied upon. If only she had one of them here now.]