Heat oven to 160C/140C fan/gas 3. Pour 100ml of the bourbon into a small, shallow roasting tin and add the star anise. Season the pork belly, put in the tin and cover tightly with foil. Bake for 3 hrs. Remove from the oven and leave to cool for at least 1 hr. You can chill the pork for up to 2 days at this stage.
Heat oven to 200C/180C fan/gas 6. Remove the pork from the tin. Using a small, sharp knife, pare away the rind from the meat, leaving a small layer of fat. Cut the meat into 2cm chunks and return to the tin. Roast for 20 mins until crisp and sizzling, turning regularly.
Meanwhile, tip the ketchup, soy sauce, honey and remaining bourbon into a small pan. Set over a high heat and bubble for 5 mins until thick and syrupy. Pour over the chunks of pork and toss to coat. Roast for 10 mins more until sticky.
Snip the chives into the sour cream, if you like, and serve alongside the pork chunks with cocktail sticks.