Soak the wakame for at least 30 minutes. Then for 10 minutes, exchange the water and rinse the seaweed at least 3 - 4 times. Frozen wakame is very salty so make sure you get most of it off or it will affect the taste. Move the wakame to a colander to drain as you prepare the other vegetables.
Thinly slice the carrot,onion, and cucumber into long strips. Chop the tomato into chunks (about ½ in cubes). Roughly chop the seaweed into bite-sized pieces as it comes in very long strips. Add everything into a mixing bowl.
Add vinegar, salt, and sugar/sweetener, and hondashi. Mix. Taste and add more vinegar, salt, and sugar/sweetener as needed.
Notes
Wakame/seaweed comes in several different forms. The one Mom bought was a long, flat beltlike version from a local Korean grocery (hence the Korean words). This one was frozen and she bought a bunch at $1.50 a bag - talk about a deal!
Mom didn't use tomatoes this time in the pictures, but she highly recommends it (we just didn't have any on hand).
Cucumbers aren't necessary, but they add a really nice color to the dish. The presentation is beautiful for parties.
Hondashi (Japanese konbu and bonito stock) is not necessary, but it adds a tasty undertone to the salad. You can usually find several packets sold in a box in Asian groceries or in the Asian section.