In a large bowl of an electric mixer, beat egg whites until foamy. With the mixer on high speed, beat in salt; then gradually add sugar, about a tableshppon at a time, beating well after each addition, until whites fold stiff, glossy peaks.
Add vanilla and beat for 1 minute. Fold in dates and walnuts.
Drop meringue mixture by rounded teaspoonfulls onto well-greased cooking sheets, spacing cookies about 1 inch apart. Bake in a 200°F oven for 1 hour or until outside is dry and set; cookies should not turn brown.
Let cool on baking sheets for about 5 minutes, then transfer to racks and let cool completely. Store airtight.