Preheat the oven to 400 degrees. Line a baking sheet with parchment paper.
Halve and pit the plums. Slice into thin wedges.
Cut the puff pastry into 3 x 5 rectangles. Arrange the plum slices on top of each piece of puff pastry.
Warm strawberry jam in a small saucepan. Brush jam over the tops of each pastry, covering both the plums and pastry. Sprinkle with sugar.
Bake 12-15 minutes or until the pastry puffs up and turns golden brown.
Serve and enjoy. Recipe makes about 8 tartlets.