Fresh walnuts are in season here in northern California, and my new favorite snack involves cracking shells in my cast-iron mortar and pestle.
These walnuts are extremely fresh. For the traditional savory snack, select nuts with large, light-colored shells. With some practice, you will be consistently able to crack open the shells while keeping the flesh of the nut fully intact, and then enjoy walnut halves (rather than the easier pieces).
For an extra treat, which you will not find in stores, select the small, dark-skinned shells. The shriveled meat inside is very sweet — it is, after all, a dried fruit.