Kulebiaka Recipe

Ingredients

• 3 ½ cups (450 g) all-purpose flour, sifted
• 1 teaspoon fine sea salt
• 1 cup (225 g) unsalted butter, chilled and cut into small cubes
• 1 cup (240 ml) cold whole milk
• 1 large egg
• 1 pound (450 g) white fish fillets (such as cod or sturgeon), skin removed and chopped
• ½ cup (90 g) long-grain rice, rinsed and drained
• 8 ounces (225 g) mushrooms, finely chopped
• 3 hard-boiled eggs, peeled and chopped
• 1 medium onion, finely diced
• 3 tablespoons unsalted butter
• 1 tablespoon fresh dill, finely chopped
• 1 teaspoon salt, plus more to taste
• ½ teaspoon black pepper
• ½ cup (120 ml) fish or vegetable stock
• 1 large egg, beaten
• 1 tablespoon cold water