I'd suggest that if you're after the store-bought style then simmer a cup of pulp with to a cup of caster sugar (depending on the sweetness of the fruit itself) and cup water. Dissolve two teaspoons of cornflour in 2 tablespoons of cold water and then mix in some of the hot pulp. Return to the pan and slowly heat up, making sure the cornflour doesn't form a leaden lump, and simmer for a minute stirring constantly. This will keep in the fridge for a week in a sealed jar or tub.
Another way to make a tasty syrup is to cook a cup of pulp with half a cup of water and a cup of caster sugar. Bring to a simmer and cook 10 minutes, stirring often. Taste for sourness - adding lime juice if needed, then pass through a fine sieve while still hot. It will be seedless but delicious, and will keep for a week in the fridge, and can be squirted over ice cream or sweet muffins, mixed into icing sugar to make frosting or drizzled into a vodka tonic with some diced strawberries or mango and fresh mint leaves - or simply made into a Pash-a-lini as we do at the Providores by putting 2 tablespoons in a champagne flute and topping with sparkling wine.
However, if I had access to plentiful fresh passionfruit as you do in NZ, then I'd simply pulp it and freeze it in ice cube trays. Once frozen I'd tip them into ziplock-bags and keep them stored away for the future.
You can never have too many passionfruit as far as I'm concerned. I remember as a child growing up in Whanganui, we had the most fruitful vine down the side of the garage and every morning when they were in season I'd take one or two with me to school and eat them by biting them open and sucking out the pulp. The bitterness of the skin never bothered me, and it, combined with the sweet and sour taste of the fruit, is one of my strongest school-day memories. And sweet and sour and bitter have remained as my strongest defining culinary characteristics when composing a dish.
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