Heat the oil and butter in a large frying pan then add the onion and garlic and cook until the onion is golden, add the beef mince and cook until well browned, stirring break up any large lumps.
Stir in the flour and cook for approximately 30 seconds, gradually add the beef stock and beer and bring to the boil. Add the tomato puree and vegemite, balsamic vinegar, mixed herbs, salt and pepper to taste. Lower the heat and simmer gently 10 minutes, then remove from the heat and allow to cool.
Assembly and Baking: Cut off a quarter of the pastry block and set it aside for the pie lids.
On a lightly floured work surface, roll out the larger piece of pastry to a square approximately 4mm thick, cut into quarters.
Line each individual pie tin, ensuring the pastry is firmly lined against the sides, leaving the pastry hanging over the edge of the tins.
Roll out the smaller piece of pastry to a square approximately 3mm thick, cut the square into quarters, cover with plastic wrap and set aside.
Fill each pastry lined dish with the mince filling, almost up to the top then add a small handful of grated tasty cheese. Brush the edge of the pastry bases with water and place the pastry lid on top. Seal edges and trim excess pastry off with a sharp knife. Whisk the egg and water together and brush over the pastry top, sprinkle with sesame seeds. Rest for 1 - 2 hours (or longer) before baking. Place directly into a preheated oven set at 220°C and bake for 25 - 30 minutes or until golden brown in colour.
Allow to cool in the tins for 10 minutes, then remove from the tins and place on a cooling rack. Serve with your favourite tomato sauce and a crisp green salad or bowl of French fries.