1) Trim the leaves off the bottom 15cm of each rosemary stick, leaving the wooden stalk exposed. Soak the rosemary sticks in water for five minutes.
2) In the meantime, slice the courgettes crosswise into 0.5cm rounds and quarter each slice of bread.
3) Assemble the kebabs by alternating 1 or 2 slices of courgettes with a tomato on the stalk of the rosemary. When there is about an inch left of the stalk put a piece of bread on the end, spearing the crusty side of the bread. Wrap the leafy part of each stick with foil. Brush the vegetables and bread with olive oil, season with salt and pepper, and grill until the vegetables are tender and the bread is toasted, turning once or twice, about 6 minutes.
4) Remove the foil and serve.