You can use an oil, or better yet, a little water and freeze. It can keep well for up to about 6 months if tightly wrapped. A Food Saver machine with the heavy weight plastic bags will offer the best as to flavor retention.

ksrogers - I was thinking of adding water, but not sure if that would work since most people used oil + nuts in their basil mixtures. I like the idea of using water since it freezes easier than oil and won't add anything extra to the herbs.

Thanks!

Unless your just wanting to make pesto, avoid the nuts. I use pine nuts, but they are partially roasted and chopped fine when searving the pesto. If you want to seson other things like tomato sauces and such, you would not need any nuts. Even for that, if you have a lot of garlic finly chop that with the basil and feeze. I would not use too much water to making the mixture, but add enough to make it like a soft paste.