Is there any way to use raw lamb? I'd like to make this recipe, but I don't have leftover lamb lying around. Should I cook it first?

As per the recipe slow cooking about ''4-6 hours or high for the next 3-5'' so no need to cook the raw lamb just wash well and add with the other ingredients

With that sort of time in the slow cooker, you don't need to cook the lamb first, but you'll add some nice color and flavor if you just sear cubes of it in the 2 Tbsp. olive oil first before adding it to the slow cooker -- no need to cook it through.

If you like, you can then deglaze the pan with some of the stock and pour that into the slow cooker too -- no tasty brown bits left behind, plus the extra pan is that much easier to wash now!