Next prepare the 700g Jerusalem artichokes. You can peel them if you want to but it's not essential and I don't usually bother. Be sure to wash them thoroughly, scrubbing off any mud if needed. Chop in half if you have any large ones. Place in a large baking dish.
Remove any damaged leaves from the outside of 350g Brussels sprouts and discard. Slice in half if you have any large ones.
Add 1 sliced onion and 2 cloves chopped garlic and drizzle with 1-2 tbsp olive oil. Toss to mix.
Add 200g cranberries and 180g cooked chestnuts for the final 5-10 minutes of cooking to heat through.
When ready to serve stir through 1 tbsp balsamic vinegar. Serve hot.