Jamie Oliver - Beef stew

I cooked this tonight - we had people round for dinner. Its one of our favourites - it so easy, just stick it in and ignore it. Our 2 year old loves it too. I added some couscous at the end tonight instead of the potatoes
Jools's Favorite Beef Stew
(Serves 4) Olive oil
A knob of butter
1 onion, peeled and chopped
A handful of fresh sage leaves
1-3/4 lb stewing steak or beef skirt, cut into 2 inch pieces
Sea salt and freshly ground black pepper
Flour, to dust
2 parsnips, peeled and quartered
4 carrots, peeled and halved
1/2 a butternut squash, halved, deseeded and roughly diced
Optional: a handful of Jerusalem artichokes, peeled and halved
1 lb small potatoes
2 tablespoons tomato purée
1/2 a bottle of red wine
1-1/4 cups beef or vegetable stock
Zest of 1 lemon, finely grated
A handful of rosemary, leaves picked
1 clove of garlic, peeled and finely chopped
Preheat the oven to 300°F. Put a little oil and your knob of butter into an appropriately sized pt or casserole pan. Add your onion and all the sage leaves and fry for 3 or 4 minutes. Toss the meat in a little seasoned flour, then add it to the pan with all the vegetables, the tomato purée, wine and stock, and gently stir together. Season generously with freshly ground black pepper and just a little salt. Bring to the boil, place a lid on top, then cook in the preheated oven until the meat is tender. Sometimes this takes 3 hours, sometimes 4--it depends on what cut of meat you're using and how fresh it is. The only way to test is to mash up a piece of meat and if it falls apart easily it's ready. Once it's cooked, you can turn the oven down to about 225°F and just hold it there until you're ready to eat it.
The best way to serve this is by ladling big spoonfuls into bowls, accompanied by a glass of French red wine and some really fresh warmed bread. Mix the lemon zest, chopped rosemary and garlic together and sprinkle over the stew before eating. Just the smallest amount will make a world of difference--as soon as it hits the hot stew it will release an amazing fragrance