Combine all ingredients in a food processor an blend until the mixture is fine and sticky.
Grab a little bit of mixture out and try to press it together with your fingers - if it seems too crumbly to hold together, add a few more sultanas or dates. If it seems too gooey, add some more oats. Keep processing until the mixture is the right consistency.
Line a small loaf tin (about 10cm x 20cm) with baking paper and spoon the mixture in. Gently press it in and smooth it out evenly.
Cover the top with baking paper and use your hand to firmly and evenly press the mixture down. You want to compact it as much as possible.
Place the whole tin in the fridge for about an hour to harden up.
Once it is cold and has hardened, remove from loaf tin and cut into slices about 3cm wide.
Store in an airtight container in the fridge, separating any layers with baking paper to prevent them sticking together.
Makes 6 bars.
Will keep in the fridge for a few weeks, or the freezer for up to three months. They will be fine at room temperature for a few days, so are great for travel snacks and lunchboxes.