Remove the heart of the garlic to prevent it becoming bitter during frying.
Briefly wash the king prawns under cold water. Use a sharp knife to remove the shell from the back of the shrimp and pull it off leaving the tail intact.
When the shell has been removed, remove the black intestinal thread if still present. Rinse the cleaned shrimp again under cold water and pat dry.
Peel the onion and cut the washed peppers into 3x3cm cubes.
Finely chop the rosemary for the marinade. Peel the garlic cloves and chop finely. Together with the olive oil, mix the sambal oelek, crushed fennel seeds and a dash of lemon juice and lemon zest in a bowl. Season with freshly ground pepper and salt. Mix the shrimp and marinade together and marinate well in a covered bowl in the refrigerator for two to three hours.
Once 2½ hours have passed, soak the wooden skewers in cold water so they do not burn on the barbecue. Alternatively, you can use metal skewers. Once the shrimp are well marinated, place onto the skewers alternating with peppers and onions, and grill for about 4-5 minutes on each side.