Whilst the first set of vegetables are roasting, take your pastry horns and grease with butter. I tried both without butter and with margarine and butter wins!
Roll out your sheet of puff pastry and cut 1cm lengths. Start at the bottom of your pastry horn and wrap around, overlapping as you go up to the top. I needed 1 and a half strips per horn. Leave a little of the metal horn showing.
Place on a baking tray for 10-15 mins.
Tip: Check your veg occasionally and cook until they are roasted but not limp.