Mix together the olive oil, soy sauce, lemon juice, salt, pepper and herbs. Marinate the prawn tails in this sauce and refrigerate for about 2 hours.
After the marinating time, first stick a cocktail tomato on a skewer, then 5 prawn tails and finally another cocktail tomato. Place the skewers in a baking dish and pour a tablespoon of the marinade over each skewer.
Then place the prawn skewers under the grill in the oven for 9 minutes.