Watercress salad with orange, asparagus & Parmesan

INGREDIENTS

• 50g Parmesan (or vegetarian alternative), grated
• 150g watercress , woody stems removed
• 2 handfuls of leaves: radicchio or red chicory
• 1 bunch asparagus , blanched for 2-3 minutes
• 2 oranges , segmented over a bowl to collect the juice
• 12 pitted black olives
• 1 tbsp sherry vinegar
• 2 tbsp orange juice
• 1 tsp Dijon mustard
• 4 tbsp extra-virgin olive oil
• 1 tsp sugar