I've never even heard of green tea ice cream. I haven't had luck with ice creams in general yet, or else I'd say "find a good green tea and add it to this ice cream recipe that I have here".
Quick Edit - Although I have heard good things about TFA Green Tea when used at very low percentages, starting at 1%.
The "green tea" flavorings are NOT the same as "matcha". They are more grassy, earthy, and taste like a more "raw" version of good Chinese tea.
Matcha is a special kind of Japanese green tea, that is ground to a powder, and whisked into hot water to make a more frothy, creamy, slightly sweet flavored tea. It is the tea used in the traditional Japanese Tea Ceremony.
I've made a "Green Tea Ice Cream"
juice, but I make my own Matcha extract, using the "crock-pot extraction" method. IT produces a fantastic flavor, but I'll be honest, teh filtering process takes DAYS because when you mix the matcha powder with PG or VG, it makes a sludge that has a consistency similar to thick crude oil. If it weren't so delicious and unique, I'd never have repeated the first batch... ;-)
https://en.wikipedia.org/wiki/Matcha