1 tbspolive oil2lamb rumps (about 350gm each), fat trimmed, at room temperature300 gmunpodded peas (see note)½white onion, thinly sliced with a mandolin1 bunchmint, leaves torn2 tbspcaramelised red wine vinegar (see note)2 tbspextra-virgin olive oil1 tbspaged balsamic vinegar820 gmcanned borlotti beans, drained, rinsed100 gmPersian feta, drained
Heat oil in a frying pan over medium-high heat. Season lamb rumps and cook, turning occasionally, until medium rare (15-20 minutes). Cover with foil and set aside to rest for 5 minutes.
Meanwhile, pod peas, then blanch (1-2 minutes).
Combine remaining ingredients (except beans and feta) in a bowl. Add beans and peas and toss to combine. Transfer to plates, slice lamb and add to bean mixture, scatter with feta and serve immediately.
Note You can substitute frozen peas if fresh peas are unavailable. Caramelised red wine vinegar is available from select delicatessens. Substitute aged red wine vinegar to taste.