The ultimate potato salad recipe with egg, apple and watercress - Gourmet Traveller

Ingredients

• 1 kg baby potatoes, such as chat
• 4 eggs
• 2 cups (firmly packed) picked watercress
• 1 large green apple, cut into julienne
• Extra-virgin olive oil, for drizzling
• Tahini mayonnaise
• 20 gm finely grated parmesan
• 1 tbsp tahini, hulled
• 60 ml (¼ cup) lemon juice
• 75 gm (¼ cup) mayonnaise
• 60 ml (¼ cup) pickling liquid from cornichons
• 8 cornichons, finely chopped
• 1 tbsp baby capers, finely chopped
• 1 tbsp each chopped dill and chives, plus extra to serve