Walnuts have great protein value. The trees grow all over the Mediterranean and are cultivated particularly on the Sorrento peninsula in Italy. Most Italian recipes using walnuts originate from Liguria.
Fresh walnuts, when their shells are still damp and the peel comes away from the kernel easily, are sweet, wet and juicy and excellent for pounding with sauces. Dry walnuts, usually those grown in the south of Italy and dried in ovens, are used for cakes, sweets, biscuits and chocolate.
Once shelled the kernels will become rancid quite quickly. Buy vacuum-packed shelled walnuts and use them soon after opening.