Mix the soy sauce, rosemary, honey, garlic, salt and pepper in the bottom of the slow cooker.
Add lamb and turn to coat in the marinade.
Cook on LOW for 5-6 hours, turning the racks 1 or 2 times or spooning the marinade over.
Check liquid levels to see if you need to add a dash of water to prevent burning of the marinade.
Remove from slow cooker, roast in 180C oven for 20 minutes to crisp up.
Meanwhile, strain the juices and skim off fat, then serve as a jus with the lamb.
Please note: I made this in a slow cooker with a tight fitting lid, that cooks very slowly. If you have a fast cooking slow cooker or a lot of evaporation, please keep an eye on the marinade as you may need to add a dash of water to keep it from burning.