Cut the zucchini lengthways into thin slices (use a mandolin if you have one), stopping when you reach the seedy middle (set this aside). Heat a griddle pan. Toss the zucchiniin a little oil to coat, then cook in batches until soft and marked with griddle lines. Drizzle a little oil into an 18cm springform tin and brush all over the base and sides. Line the base with a circle of baking parchment. Use the zucchini to line the tin, overlapping them across the base, up the sides and over the edge – you need enough overhang to cover the top and the filling, so you may need to double up on slices up the sides. Scatter 2 tbsp gluten free breadcrumbs over the base.
Heat the oil in a large frying pan. Meanwhile, finely chop the centre pieces of zucchini and add to the pan. Cook for about 5 mins until the zucchini has softened, then set aside to cool.
Heat oven to 180C/160C fan/gas 4. Mix the cooled veg, the peppers, chives, parsley, lemon zest, gluten free breadcrumbs, egg, pork, chili and plenty of seasoning in a bowl. Pack the mixture into the zucchini-lined tin, pressing it firmly into the edges and flattening the top – try not to move the zucchini slices too much. Fold over the overhanging zucchini to cover the top of the pie and press down firmly.
Place the tin on a baking tray – some juice may leak out of the tin so you will need the tray to catch this. Bake for 1 hr 15 mins – if you have a meat thermometer, the temperature should read at least 70C. Cool in the tin for 10 mins. Remove the pie from the tin, pouring away any juices, and flip over so that the neater side is facing up. Remove the baking parchment and leave to cool completely, then store in the fridge. Transport in a cooler bag and serve in wedges.