1.Preheat oven to 220°C (200°C fan-forced). Line 2 baking trays with baking paper. Combine mince, seasoning and onion in a bowl. Place pastry on prepared trays.
2.Top with lamb mixture, leaving a 2cm border. Brush border with a little egg. Fold in border to create an edge. Brush with a little more egg.
3.Arrange potato over lamb mixture; sprinkle with parmesan. Bake for 15 minutes or until pastry is golden and lamb is cooked.
4.Combine tomato, onion and dressing in a bowl; toss to combine. Serve tarts topped with salsa.