To begin, combine warm milk, sugar and yeast in a bowl. Let it sit for 10 minutes until foamy. In a large bowl, mix flour and salt, then add the yeast mixture, egg and melted butter. Knead until smooth and elastic. Cover and let rise for 1 hour. Move to preparing fillings.
In a pan over medium heat, melt the butter and sauté the cabbage until soft and lightly golden, about 10–12 minutes. Season with a little salt. Set aside to cool before layering.
Heat oil in a small pan. Cook the onions until translucent and lightly browned. This adds depth to the filling. Set aside. Transition to preparing fish and rice.
Season the salmon fillet with salt and pepper. Steam or poach gently for 6–8 minutes until just cooked. Flake into bite sized chunks and set aside.
In separate bowls, have your cooled cabbage, cooked rice, chopped eggs, sautéed onions, flaked salmon and fresh dill ready. Light seasoning can be added to each component if preferred. Move to shaping the pie.
Preheat your oven to 190°C (fan 170°C). On a lightly floured surface, roll out the dough into a large rectangle about ½ cm thick. Begin assembling the filling.
Place the rice in a narrow strip down the centre of the dough. Follow with sautéed onions, chopped eggs, flaked salmon, cooked cabbage and a sprinkling of dill. Gently press each layer to keep it compact. Transition to sealing.
Fold the long sides of the dough over the filling, overlapping slightly. Pinch the ends to seal well. Carefully transfer the pie onto a parchment lined tray, seam side down. Brush with egg wash.
Bake in the preheated oven for 35–40 minutes, or until golden brown and firm to the touch. Allow to cool slightly before slicing. Move to final presentation.
Slice into generous pieces and serve warm. Kulebyaka pairs beautifully with a dollop of sour cream or a spoonful of mustard. Serve with a simple cucumber salad or pickles to contrast the richness.