Freezing mint?

I freeze mint quite regularly, and because you use it chopped, I’d probably go with the ice-cube method. Chop the fresh leaves, put them into an ice-cube tray, cover with a little water and freeze. Once frozen, you can transfer the cubes to a freezer bag and just take out however many you need.

If you want to use the mint without adding water, you can also freeze the chopped leaves in a thin layer in a bag or container and break off what you need. I find that more convenient for cooking, while the ice cubes are handy for drinks and sauces.

I’d also freeze it while the leaves are still young and in good condition rather than waiting until later in the season. If you have several different types of mint and aren't sure which one you have, this herb identifier can be very useful for checking them botanapp.com/identifier/herbs

Frozen mint won't have quite the same texture as fresh mint once thawed, but the flavour holds up pretty well.