Made everything from scratch here! I picked up the plums from a local farmers market, but end of August/early September is tricky for fruits around northern Ohio since everyone is trying to get their corn, soy, pumpkin, and squash harvested and off to market. While this was a fun one, to quote Mary Berry, "life's too short to make your own puff pastry". Normally i only make my own for meat pies since you wont find any puff pastry with mustard in it state side.
Mustard in puff pastry sounds intriguing. I haven't bothered to make my own yet, as I quite agree with Mary.
Last year i made a stargazzy pie for the Midsummer's Night's Bake challenge and the piff pastry called for mustard in the pie crust,and the pie was absolutely delicious. Since it doesn't require countless laminations, I highly recommend it!