I've made bacon-banana ice cream.

It's only dry ice... I work with plenty of it everyday. As long as you don't handle it with too wet or dry hands you'll be fine, but your shirt/apron will do the trick just right. I've been making ice cream with an ice cream maker, boy it's useful. Getting the anglaise (custard) right is hard.....

A proper blender is most recommended for banana, because when I tried to make banana ice cream the other day, hand-mashing gave a great deal of problems with the sieve. Freeze the banana before you blend it too.

For your acid, I would go for either 1) (pickled) plum or peach or, if you can handle the colour matching, kiwi (difficult...?) ; or 2) make your gels sour e.g.: red and blue (from fresh strawberries and blueberries). I'm not exactly sure what you are trying to do with the gels from what you said, so I can only offer as much. Can't help you with the tuilles, sorry.

Or... you know what... what about yoghurt for the acid? Handle with care. I was about to say sour cream, but seems to disagree with vanilla. All that I've suggested seem a little difficult to go with the vanilla and the caramelised nuts... arrgh.

Here's an interesting but random thought for you, something a little japanese. Black sesame ice cream and white sesame ice cream. One scoop of each, and you can have enormous ways to plate it.

Keep us updated. You've made me really interested (for someone who knows nuts about making food).

Hadriel
[I should say that I lean on the "Beauty lies in simplicity" school of thought]