Sausage Rolls

Pastry

• ⅛ tsp salt
• 6 oz unsalted butter, in pieces, frozen
• 8 oz all-purpose flour, plus extra to dust
• 2 ½ oz ice water

Sausage Filling

• 4 oz yellow onions, quartered
• ⅛ tsp ground black pepper
• 1 tsp mixed dried herbs
• ½ tsp salt, to taste
• 16 oz ground pork sausage, crumbled
  of 16 oz uncooked pork breakfast sausages, crumbled
• 1 large egg, whisked, to brush