1Combine lamb, 2 tbs oil and 2 tsp rosemary in a bowl. Cover and marinate for 1 hour or overnight. Bring to room temperature before cooking.
2Meanwhile, using a fork, combine butter, black garlic, 1 tbs honey and remaining 1 tsp rosemary in a bowl until well combined.
3To make the dressing, combine vinegar and remaining 1 tbs oil and 2 tbs honey in a bowl and whisk until well combined, then set aside.
4Preheat oven to 180°C. Grease a baking tray and line with baking paper.
5Place lamb, fat-side down, in an ovenproof frypan and place over high heat. When hot, cook for 5 minutes on one side, then turn and cook for 2 minutes or until browned. Transfer to oven and cook for 15 minutes for medium-rare, or until cooked to your liking. Transfer to a plate, top with small pieces of butter mixture and cover to keep warm.
6Heat a large chargrill pan or barbecue to high heat. Grill corn, turning occasionally, for 15 minutes or until grill marks appear. Transfer to a plate and brush over some butter mixture. When cool enough to handle, use a sharp knife to cut kernels from cob. Transfer the kernels to a bowl and toss through parsley, mint and vinegar dressing.
7Melt remaining butter mixture.
8Slice rumps into large pieces. Divide lamb and salad among serving plates, scatter with manchego and drizzle with melted butter mixture to serve.
2 x 450g lamb rumps
1/4 cup (60ml) extra virgin olive oil
3 tsp finely-chopped rosemary leaves
125g unsalted butter (softened)
2 black garlic cloves (mashed)
1/4 cup (60ml) runny honey
2 tbs red wine vinegar
4 corn cobs (silks removed)
1/2 bunch each flat-leaf parsley and mint (leaves picked)