If you opt to include the seaweed, rinse and soak hijiki or organic arame in 1 cup warm water until softened, about 10 minutes. Drain and squeeze out excess water when ready.
While hijiki or arame is soaking, chop cabbage, scallion and place in a bowl. Cut tomato in half and squeeze out seeds, cut out pulp, and slice in thin strips.
Whisk together dressing ingredients and toss with cabbage, tomato, and scallion (and hijiki or arame and/or chopped chicken if so desired). Sprinkle with sesame seeds.
Serves 4 If you're concerned about the safety of sea vegetables, read this article