In food processor, purée dates, orange rind, orange juice and salt. (If food processor has a small bowl, do this in batches to avoid a mess.)

Add 2 cups/500 mL of the walnuts and pulse until finely chopped. Add remaining walnuts and pulse until coarsely chopped with some larger pieces remaining.

Scrape mixture into parchment paper-lined 9-inch/23 cm square baking dish; smooth top. Bake in centre of 200°F/95°C conventional or convection oven until no longer sticky and fairly dry, about 3 hours. Let cool completely.

With moistened knife, cut into eighteen 3- x 1-1/2-inch/8 x 4 cm bars; wrap individually in plastic wrap. Store in airtight container for up to 1 month.

Makes 18 bars.