I’ve done this to accompany a Dal Bhat, a match made in heaven, or as near to it as you can get in the Himalayas.
In Nepal they would use mutton or goat rather than lamb, but it makes for a close substitute in the UK. Not that mutton is that hard to get, if you really want it, lamb is plenty good enough.
It starts with marinating and as always, the longer the better, but even if you can only manage an hour, take it, it’s totally worth it. How do you make Nepalese Lamb Pakku?