Roast lamb with hasselback potatoes

Use a small, sharp knife to make at least 30 small, deep incisions all over lamb. Halve garlic bulbs, so cloves fall away at top and remain attached at base. Peel and slice tops and keep the base halves for later. Use your fingers to push garlic slices into each lamb slit. Pull off some small sprigs of rosemary and thyme, keeping stalks on, and poke into the slits. (This can be done a day ahead. Cover lamb and chill. Remove from the fridge 1 hour before roasting).

Preheat oven to 190°C fan-forced (210°C conventional). Slice potatoes (see easy steps to hasselback potatoes, below). Slot a bay leaf into the middle slit of each potato. Tip potatoes into a large roasting pan with reserved garlic and remaining rosemary and thyme. Drizzle with half the oil and season, then toss to coat and turn potatoes so they’re all cut-side up. Nestle lamb in middle of pan, pushing potatoes to the outside, then rub lamb with remaining oil and lemon juice and season generously.

Roast for 1½ hours, basting potatoes and shaking the pan occasionally, until lamb is dark brown and potatoes are crisp and golden. The lamb will be pink in the middle but cooked. For rare, cook for 10 minutes less, and for well done, 15 minutes more. Remove lamb from pan and rest for 15 minutes, putting potatoes back in the oven if needed. Serve drizzled with Green Olive and Herb Dressing (see below).