Process flour and butter until crumbly. Add egg and enough of the water to make mixture come together. Knead pastry on floured surface until smooth. Cover; refrigerate 30 minutes.
For the beef filling, heat oil in large saucepan; cook onion and beef, stirring, until beef is browned. Stir in undrained tomatoes, paste, sauce and stock; bring to the boil. Reduce heat; simmer, uncovered, about 20 minutes or until thick. Cool.
Oil six ⅔ cup (160ml) pie tins. Divide pastry into six portions; roll each portion between sheets of baking paper until large enough to line tins. Lift pastry into tins; press over base and sides. Trim edges. Refrigerate 30 minutes.
Cut six 11cm (4½-inch) rounds from puff pastry. Refrigerate until required.
Preheat oven to 200°C/400°F.
Line pastry-lined tins with baking paper; fill with dried beans or rice. Place tins on oven tray; bake 10 minutes. Remove paper and beans; bake further 5 minutes. Cool.
Fill pastry cases with beef filling; brush edges of pastry with extra egg. Top with puff pastry rounds; press edges to seal. Brush tops with extra egg. Cut steam holes in top of pies.
Bake pies about 20 minutes or until pastry is browned lightly.
