Tea leaves (of any sort) need to be dried before use.
Quote:
"If you have your own olive trees, you can make your own tea.
The key is to ensure you have good quality leaves not sprayed with pesticides.
1. Pick healthy leaves without blemishes mid-morning when any dew has dried.
2. The leaves should ideally be oven-dried at just below 150 deg F. (65 deg C).
Tests indicate that more active ingredients are lost by air or sun-drying than oven drying.
If you air-dry the leaves, preferably do not lay them in direct sunlight which will cause more oxidative damage and reduce their benefits.
2. When dry, crush the leaves by hand, removing the stalks and place in paper packets for storage before use.
3. Make tea in a teapot as you would normally make it, using approximately a teaspoonful of leaves per cup."
Source:
https://nanaymiriam.wordpress.com/2012/12/14/how-to-make-olive-leaf-tea/