In a mixing bowl, combine the crab meat, chili sauce, mustard, mayo, Worcestershire sauce, spring onion and herbs. Mix well. Cover and refrigerate until needed.
Using a serrated knife, cut a very thin slice from the stem end of each tomato. Carefully scoop out the pulp and seeds with the tip of a teaspoon.
Sprinkle the insides of the tomato shells with sea kelp. Invert them on a paper towel and let them drain for 15 minutes to get some of the water out of the tomatoes. Using a small spoon, stuff the tomatoes with the crab, mounding the filling slightly on top. Serve cold.