Step 1: Take as many cuttings as you want. Use the top 6 - 10cm of each stem.
Step 2: Rinse lightly.
Step 3: Cut finely directly into an ice-cube tray.
Step 4; Drizzle over with some olive oil
Step 5: Fill with water & freeze.
Take cuttings every few weeks, preferably early in the morning. Enjoy during the off-season.
Of course, there's more than one way to skin a cat. Here's an alternative method. (Thanks to Robin from Robin's Kitchen)