Thaw the puff pastry beforehand overnight in the fridge or in a sunny area for quicker thawing.
Find a large round stencil/bowl/pot - anything you can use to mould out a rough circle from the pastry. Cut out the circle.
Transfer the dough onto the wire rack.
Slice each plum into eight slices and arrange them in a single layer leaving about 3-4cm from the edge of the pastry.
Sprinkle sugar on top of the plums and squeeze the juice of half the lemon on to the plums.
Place the galette into the oven and bake for about 35-40 minutes with the foil on until the plums are cooked.
Remove the foil and allow the pastry to brown.
Served with a sprinkle of icing sugar and some fresh cream or ice cream.