Passiflora actinia fruit.
This is the only fruit that I have grown outside in UK that tastes really good. It is very tasty with a lemony acidic taste & a kerosene like smell. Kerosene occurs naturally in some fruits e.g. mangos. Its taste is helped by a good sunny summer. Less sun gives slower ripening (December instead of October) and poorer taste. It is not grown commercially to my knowledge, probably because the fruit are quite small, about half the size of P. edulis, and it does best in cooler mountain conditions., where it will crop twice a year.