Many feel that freezing herbs in oil is a better way to make ice cube herbs.
Preserving herbs in oil, just as in water, will eliminate or at the very least reduce some of the browning that herbs sometimes get in the freezer.
I find that in some cases this true. Harder herbs such as garlic, thyme, oregano, fennel and rosemary that would normally be cooked with a recipe as opposed to being simply added for flavor.
Soft herbs such as basil, mints, and dill which are generally added raw to a dish are best preserved in water ice.
Choose unblemished fresh herbs.
I prefer to chop or mince them beforehand.
Pack the wells of ice cube trays about 3/4 full of herbs.
Pour olive oil or melted, unsalted melted butter over the herbs. Do not add salted butter. The presence of salt reduces the freezing point. The more salt in the water, the lower the freezing point will be. It also interferes with the natural herbal flavors.
Freeze the solid and then transfer to cold storage bags - the same as with water ice herbs.
It is advisable to label each bag with the date and type of herb.