Zucchini and farro salad with toasted hazelnuts

Ingredients

• 200 gram farro (pearled spelt), rinsed and drained
• 2 zucchini (courgettes), thinly sliced lengthways using a mandoline or very sharp knife
• 1/2 red onion, thinly sliced
• 6 prunes, pitted and finely chopped
• 50 millilitre apple balsamic vinegar, regular balsamic vinegar or sherry vinegar
• 1/2 teaspoon dijon mustard
• 50 millilitre (1⁄4 cup) vegetable oil
• 60 millilitre (1⁄4 cup) olive oil
• large handful (3⁄4 cup) mixed herb sprigs, such as mint, parsley and dill
• 50 gram (1/3 cup) toasted hazelnuts, roughly