In a heavy non stick pan sauté onions and bacon until the onions are translucent and most of the bacon fat has rendered.
Add ground pepper to taste.
Leave this mixture to cool completely while you are making the dough. I usually make the bacon/onion mix the day before and leave it in my fridge until I am ready to use it. The bacon mixture is easier to work with when cold.
Place yeast and water in a small bowl, put aside for the yeast to activate. It will froth up.
In a small saucepan add butter, milk and sugar. Warm over a low heat until butter has melted and sugar has dissolved into the milk.
When milk mixture has cooled to lukewarm stir through beaten egg, yeast and water.
Place two cups of the plain flour and salt in a large bowl, pour liquid over and stir to combine.
Once combined add the remaining flour. Mix until all ingredients have come together, then leave to rest in the bowl for 10 minutes.
Once rested turn dough out on to a lightly floured surface and knead until dough is smooth and elastic, about 5 - 10 minutes.
Place dough back in to a lightly oiled bowl and cover. Leave dough to raise, around 1½ hours or until doubled in size.
Preheat oven 180 deg C (360 deg F)
Once dough is ready, start pulling off a walnut size pieces of dough. Work them in to a ball in your hand then tease them out to a circle. Place a tablespoon of the bacon mixture, and bring the edges of the dough together. Seal the bun in a torpedo shape.
Place formed buns on a baking tray that has been lined with baking paper.
Mix the beaten egg and water together to make an egg wash. Brush egg wash mixture on buns. Place buns in oven and bake until golden, 12-15 minutes.Repeat with the remainder of the mixture and dough.