Put the diced lamb into a mixing bowl. Add the harissa, tomato purée, red wine vinegar, lemon zest & juice and some black pepper – don’t add salt yet. Mix together making sure that all lamb pieces are well coated. Marinate for at least an hour in the fridge, preferably overnight.
If you’re using wooden skewers, soak them in water for at least 30 minutes.
Cut the red pepper into 3cm pieces.
Take the lamb out of the fridge and add the pepper pieces. Mix well. Season with salt.
Thread the meat & pepper pieces, alternating, onto the skewers (metal or the pre-soaked wooden ones).
Heat a grill, barbecue or griddle pan.
Cook the lamb skewers for approx. 10 mins, turning regularly, until cooked to your liking.
Serve warm.