Place the new potatoes in a pan of lightly salted boiling water. Cover and simmer for 15 minutes or until tender. Drain and allow to cool slightly.
Heat the oil in a non stick frying pan and fry the sauages for 15 minutes or until cooked. Add mushrooms and cook for 2-3 minutes.
Mix together the potatoes, sausage and mushrooms and stir in 2 tbsp BBQ sauce. Onto each kebab thread 2 or 3 pieces of potato, 1 tomato, 1 mushroom and 2 slices of sausage. Place under a preheated grill or barbecue for 1-2 minutes to finish off, brushing with any remaining BBQ sauce.
For the dip, mix remaining 1 tbsp BBQ sauce with the mayonnaise and serve with the kebabs.