Discard neck from turkey. Rinse turkey under cold water; pat dry inside and out with absorbent paper. Using kitchen scissors, cut along each side of turkey's backbone; discard backbone. Turn turkey skin-side up; using heel of hand, press down on breastbone to flatten turkey.

Using a mortar and pestle, grind peppercorns, star anise, seeds and salt until crushed coarsely. Dry-fry peppercorn mixture with chilli and spices in a small frying pan until fragrant. Remove from heat; stir in oil. Rub spice mixture all over turkey.

Place turkey, skin-side up, in a deep disposable baking dish. Cook turkey in covered barbecue, using indirect heat, following manufacturer's instructions, about 2 hours. Remove from barbecue; cover loosely with foil, rest 10 minutes.

Make peach and cranberry chutney. Place peaches in a large bowl, cover with boiling water for 30 seconds; drain. Peel away skin; remove seed. Chop peach flesh coarsely; combine in a medium saucepan with remaining ingredients. Bring to the boil. Reduce heat; simmer, uncovered, stirring occasionally, about 1¼ hours or until chutney thickens.

Serve turkey with chutney.