Dice lamb into 3cm cubes. Combine marinade ingredients. Marinate diced lamb for about 30 minutes, or overnight if time allows.
Toss potatoes, olive oil, salt, pepper and lemon juice in a baking dish and cook in a hot oven (200 degrees Celsius) for 45 minutes or until crispy and golden.
Meanwhile thread lamb onto oiled metal skewers or pre-soaked wooden ones. Reserve marinade as a baste.
Cook on a hot BBQ plate or chargrill until well sealed (about 5-6 minutes), turning occasionally and basting with marinade.
For rare, remove immediately after sealing. For medium or well done, move to the cooler part of the BBQ or reduce heat to medium/low and continue cooking about 3-4 minutes for medium, 4-5 minutes for well done, turning occasionally.
Test kebabs are cooked to your liking by squeezing with tongs rather than cutting them (rare feels soft, medium a little firmer). Cover and rest about 1 minute before serving to retain juiciness.
Serve with the crispy roast potatoes and seasonal vegetables.
Tip: If you have a healthy rosemary bush in your garden choose some stems to use instead of skewers. Strip the leaves and soak before using, as you would for wooden skewers.