Anchovies and rosemary are a perfect match for lamb, adding
just the right touch of savouriness and fragrance. We've roasted
the lamb on top of the potatoes and fennel, but if you prefer your
vegetables crisper, roast them in a separate pan.
6 anchovy fillets, coarsely chopped4 garlic cloves, coarsely chopped, plus 1 head extra, halved 1 tbsp finely chopped rosemary, plus 2 extra sprigsFinely grated rind of 1 lemon, juice of ½ lemon1 tbsp olive oil, plus extra for drizzling1boneless lamb loin (about 1.2kg), fat trimmed2 small fennel bulbs, fronds reserved3Desiree potatoes, scrubbed and cut into wedges1 onion, cut into wedges150 ml chicken stock 100 ml dry white wine1½ tbspextra-virgin olive oil2 tsp white wine vinegar
Preheat oven to 200C. Pound anchovies, garlic, rosemary, lemon rind and a pinch of salt with a mortar and pestle to a rough paste, season to taste with freshly ground black pepper, then stir in olive oil. Place lamb loin flat on a work surface and spread with anchovy paste, roll into a cylinder then place rosemary sprigs on top. Secure at intervals with kitchen string, then stand at room temperature to marinate for 30 minutes.
Cut 1 fennel bulb into wedges and combine with remaining vegetables and head of garlic in a roasting pan, and season to taste. Place lamb on top, drizzle with a little extra olive oil, add stock, wine and half the lemon juice to pan, then roast until cooked to your liking (50 minutes to 1 hour for medium-rare, and internal temperature reads 54C-58C on a meat thermometer). Cover with foil and set lamb aside to rest for 15 minutes. Discard string.
Meanwhile, thinly shave remaining fennel on a mandolin and place in a bowl of iced water to crisp (10-15 minutes). Drain well, add fronds and, just before serving, dress with extra-virgin olive oil, vinegar and remaining lemon juice. Season to taste, toss to combine and serve with sliced lamb and pan vegetables.