Adding description while avoiding authorial intrusion

When writing fiction it it best to avoid diving straight into description, since this is total 'authorial intrusion'; in other words, the author's voice shouts out to interrupt the 'suspension of disbelief' you have lulled your reader into while caring about your characters. Looking at a scene through your character's eyes and observations is one way to achieve this. The following is an example taking from the novel I am presently writing:

I suddenly found myself observing her as a stranger might in order to gauge what Julia perceived. I was very ware of the shrillness to her voice and, although her English was excellent, I realised how Julia might notice her speech was still modulated by a German staccato; each word was sharply enunciated. I was also aware of an aroma of stewed apples. She’d always had a thing about apples. I’d practically lived on them as a kid. The house always smelled of apples.