His eyebrows arch rather spectacularly at that, practically disappearing into his bangs for the span of a few heartbeats. He'd expected that either the carrots were going to be used or they weren't, not to be handed only one solitary vegetable, and he has to resist the urge to make a comment to that effect. However, he's able to manage that easily enough and it's only a matter of moments before his eyebrows go back to where they were originally, followed by a brief shrug.

"fair enough. I'll be back shortly."

Fortunately for Avery (and everyone's dinner), one of the things the Doctor's managed to impress on him over the years is that hygiene is a good thing. So even though he does get teased about that from time to time, overall he's much better at keeping clean - and when she says 'thorough', he takes her at face value, making sure both his hands and the carrot are very very clean before he goes back. He even goes so far as to get the dirt out from under his nails - or, well, as much as he can manage without a scrub brush, anyway.

"Right. Is that clean enough, then, or should I have another go at it?"