Polish vegetable salad (Insalata Russa)

Salad

• 300 g carrots peeled and cut into pieces (4 cm)
• 200 g parsnip peeled and cut into pieces (4 cm)
• 100 g celeriac peeled and cut into pieces (4 cm)
• 430 g potatoes peeled and cut into pieces (4-4.5 cm)
• 500 g water
• 4 eggs
• 70 g leek white part only, cut into slices (1.5 cm)
• 250 g dill cucumbers cut into pieces (3 cm)
• 180 g apple cut into quarters and core removed
• 220 g frozen green peas thawed (optional)

Dressing

• 280 - 300 g mayonnaise (see Tips)
• 1 tsp Dijon mustard
• ½ tsp ground black pepper
• 1 pinch sea salt
• 1 - 2 sprigs fresh parsley leaves only, finely chopped, for garnishing