Heat your oven to 180°C/Fan 160°C/Gas 4. Put a roasting tin in the oven to heat up. Put a large pan of water on to boil.
Scrub the new potatoes and halve or quarter them so they're all roughly the same size. When the water is boiling, add them to the pan. Simmer for 5 mins.
While the potatoes are simmering, halve the pepper and scoop out the seeds. Roughly chop the pepper. Trim the courgette ends and roughly chop the courgette.
Drain the potatoes. Add 1 tbsp oil to the hot roasting tin. Tip in the potatoes. Add the chopped veg. Season with a pinch of salt and pepper. Toss to mix, making sure you end up with an even layer of veg in the tin. Roast on the top shelf for 20 mins.
While the veg roast, finely grate the zest from the lemon into a bowl. Keep the lemon for later. Finely chop the parsley, leaves and stalks, and the oregano leaves. Add to the zest and stir.
Cut 2 rectangles of baking or greaseproof paper around 30cm x 40cm (see tip). Lay one sheet on your work surface and heap half the fish pie mix in the middle off it. Scatter over half the lemon and herb mix. Season with salt and pepper. Lift two sides of the paper up and hold them together. Fold down to make a pleat. Tuck the short ends underneath to make a parcel. Repeat with the remaining fish, herbs and paper.
After 20 mins roasting, move the veg down to the middle shelf. Put the parcels on a baking tray on the top shelf. Bake for 10 mins. The fish will be opaque and flake easily when you open them (mind the steam) and the roast veg will be tender. Serve the parcels and veg with lemon wedges for squeezing.