I'm putting half a leg of lamb (bone in) in the slow cooker and am going to bung potatoes and veg in so it's like an all-in-one roast. i've done this before and it was delicious but I can't for the life of me remember whether I par-boiled the potatoes first. D'you reckon I'd need to? I was hoping to get away without par-boiling, could I if I cut them up fairly small? Also what about liquid - I drizzle balsamic vinegar over it, would the potatoes cook in just that and any fat that comes out, or do I need extra liquid? Finally, any ideas about how long it would take? Thank you!