1 tablespoon extra virgin olive oil, plus extra for drizzling
1 tablespoon finely chopped oregano
300g baby spinach leaves
400g canned cannellini beans, rinsed and drained
Instructions:
Whisk 60ml of the truffle oil with garlic, mustard and 2 teaspoons of salt.
Place lamb in a baking dish, rub the oil mixture all over it, cover and set aside for 20-30 minutes to come to room temperature. Meanwhile, preheat oven to 220°C. Cut potatoes into bite-sized pieces and onions into thin slivers.
Toss with lemon zest, salt, remaining truffle oil, olive oil and oregano and place in the baking dish around the lamb.
Place in the oven and cook for about 40 minutes for medium (until the internal temperature registers 65°C on a meat thermometer), or until cooked to your liking. Meanwhile, heat a large frying pan over low heat.
Add a drizzle of olive oil and spinach. Cover and cook for 5-10 minutes, stirring often, until wilted.
Add beans and salt and stir for a minute or so to heat beans through. Remove from heat, cover pan and set aside to keep warm. Remove lamb from the baking dish, cover loosely with foil and set aside in a warm place.
Increase oven to 250°C, stir potato and onion mixture well and return to the oven for 10-15 minutes, until potatoes are crisp and golden. Arrange potato and spinach mixtures on a platter. Slice lamb, place on top and serve.