To prep, preheat the oven to 400F and grease a 9 inch metal pie plate generously with butter.

Combine rhubarb, butter, cornstarch and sugar (minus 1 tbsp) together into a bowl and mix to coat. In a smaller bowl, rub the orange zest together with the reserved 1 tbsp of sugar until mixed and not clumping. Add to the rhubarb mixture and toss until combined.

Tip the whole mixture into the bottom of the pie dish and spread evenly, arranging into a pattern if desired. Top with the puff pastry, being sure to tuck the edges of the pastry under the fruit at the edge of the pan. Prick top generously and cut a small cross into the centre of the pan to vent.

Bake in oven for 25 to 30 minutes, or until pastry is golden, puffed and cooked through, and the fruit underneath is bubbling. Let cool in the pan 10 minutes before loosening the edge of the pastry with a knife, then inverting onto a serving plate in a quick motion. Arrange any wayward fruit and serve immediately with ice cream.