Clean and wash the zucchini and slice or cut them lengthwise into thin slices. Place the slices next to each other and salt lightly.
Wash the thyme, shake dry and pluck the leaves. Rinse fish, dab dry and cut into 6 pieces. Season with salt, thyme and fennel.
Dab zucchini dry. Place 2 slices crosswise. Place 1 piece of fish in the middle of each slice, wrap it in the zucchini slices and tie it with kitchen string. Brush the packet with oil. Grill on the hot grill for 2-3 minutes on each side.
To prevent the kitchen yarn from burning, cut the ends short. If you want to be on the safe side, use an aluminium bowl. Then grill for about 5 minutes on each side.