how to match indoor audio to outdoor audio

As others have said, you can't really do this...however, you could mix some of the outdoor ambiance into the indoor clips in the hope of making the contrast less obvious. Good idea? Probably not, but depending on what you're trying to do., it might help.

Post sync.  If it's not to picture just re-record.

Basically, I'm afraid you can't really do this. Your indoor example will have the room tone embedded into its sound, and short of resynthesising it (which always makes things sound weird) you can't get rid of it. You stand a better chance of doing this the other way around, by playing the outdoor clip indoors and re-recording it. The only other thing you can do is to roll off the bass on the indoor clip but that still won't get rid of the room tone.