Tuna and Spring Onion Quiche

Pastry

• 300 g plain flour
• 150 g unsalted butter, chilled, diced
• ½ tsp fine sea salt
• 2 tsp dried thyme
• 1 egg yolk, from medium egg
• 50 g water, ice cold

Filling

• 75 g spring onions, sliced (2 cm)
• 200 g Cheddar cheese, cut in pieces (2 cm)
• 230 g tinned tuna, in water, drained
• 250 g crème fraîche
• 250 g milk
• 4 large eggs
• 1 tsp Dijon mustard
• ½ tsp fine sea salt
• ½ tsp ground black pepper