1. Heat your oven to 220°C.

2. Roughly chop the tarragon, garlic and salt together and rub all over the lamb shoulder. Place the lamb in a heavy, lidded casserole dish and scatter around the pickling onions, putting a few under the lamb to raise it from the bottom of the pot. Add the white wine and a cup of water and bake, covered, for 30 minutes.

3. Reduce the heat to 120°C and bake for a further 7 hours until the lamb is falling apart.

For the potatoes
4. The potatoes require a hotter oven than the lamb so unless you have a second oven, you'll have to wait for the lamb to finish, then keep it warm while you cook the potatoes.

5. Turn the oven up to 200°C. Place the potatoes in a large pot of cold water and bring to the boil. Simmer for 6 minutes, then drain and return to the pot.

6. Place the pot of drying potatoes over low heat for a minute or two until the edges of the potatoes turn chalky white. Place the lid on the pot and give it a good shake to rough up the edges.

7. Empty the potatoes into a large baking dish and toss with the olive oil and salt. Roast for 45 minutes to an hour, tossing occasionally, until the potatoes are golden and crisp.

8. Boil the peas until tender (about 3 minutes), then stir through the butter and a little salt.

To serve: Place most of the peas on a serving dish, then place the lamb and onions on top. Break apart the lamb and scatter with the remaining peas. Grind plenty of black pepper on top and serve the lamb and peas with the potatoes.

And ... The best thing about slow cooking is that you get fantastic flavour with very little effort. Just throw it all in the oven and let time do it all for you.