I recently found fresh passion fruit in Oliver's for $20 per 100 grams. I've been told there are several varieties of this exotic fruit, but the only ones I've seen are the type pictured here. This fruit doesn't look inviting: they're slightly smaller than a billiard ball, and when unripe, the skin is smooth and the same colour as that of an unripe avocado. Buy them when the skin has darkened to a purpleish mangosteen colour and is slightly wrinkled. Passion fruit has a distinctive smell and flavour - sharp but sweet and highly perfumed. The soft flesh is a bright egg-yolk yellow, and has lots of edible seeds surrounded by pulp. You can sometimes find frozen passion fruit puree - the seeds have been strained out, and it's actually easier to use than the fresh fruit.
Pastry chefs love to use passion fruit as a sauce: its bright sunny colour looks great on a white plate, especially when contrasted with the deep red of a raspberry sauce. Halve the fresh fruit and scoop out the flesh and puree in a food processor or blender. Don't over-process - that turns the seeds to liquid, which discolours the puree. You can strain the puree or not, as you wish (I don't if I'm using it for a sauce, but do if it's for sorbet). Mix with an equal measure of sugar syrup (equal parts water and sugar, boiled until the sugar is dissolved) and a little fresh lemon juice.
M at the Fringe makes a wonderful pavlova with fresh fruits and passion fruit sauce - the sharp flavour tempers the sweetness of the meringue, which can be cloying otherwise.