In a large bowl put the chunks of lamb ready for the marinade to be added to them.
To make the marinade place the mustard, vinegar, olive oil, salt, pepper, sage, rosemary and garlic and mix well together before then pouring over the lamb.
Use your hands and mix all these ingredients together to make sure that all parts of the lamb are then coated in the marinade.
Once you have done this cover the bowl over and place in the refrigerator overnight.
Whilst the barbecue is heating up you can now start to make the kebabs.
If you are using wooden skewers make sure that they have been soaking in some water for at least 30 minutes.
To make each kebab thread on pieces of meat along with some of the mushrooms, tomatoes, pineapple and cherries and then place on the lightly oiled barbecue grill to cook.
Each kebab should remain on the barbecue for around 12 minutes and you should be turning them over frequently to prevent them from burning.
It is important that whilst cooking the kebabs that you baste them with a sauce made from the melted butter, pineapple and cherry juice.
This will help to enhance the flavor not only of the lamb but the other ingredients on the kebabs.