Soak eight wooden skewers in cold water for at least 30 minutes. Alternatively, use metal skewers.
Put the butter in a bowl, add the parsley and garlic and blend together using a fork. Chill in the fridge.
Cut the liver into 3cm square pieces and cut the bacon into 3cm strips. Cut the tomatoes into halves, then cut each half into three to give six wedges from each tomato. Scoop out the seeds. Preheat a grill pan to a moderate heat.
Arrange alternate pieces of bacon, liver and tomato (three wedges per skewer) on the skewers. Brush lightly with oil and season with pepper.
Lay the kebabs on the grill pan and cook for 6–8 minutes until the liver is just tender, giving them a quarter-turn every few minutes.
Put the kebabs on warm serving plates, top with knobs of the herb and garlic butter and serve garnished with parsley.
This recipe would also work well with small squares of steak or lean lamb. Serve with soft polenta and wilted English spinach.