Thinly slice the onion and green onion. Soak them in cold water to remove bitterness.

Separate the broth from the canned sea snails and place the snails in a large bowl. Cut them into bite-sized pieces if needed.

Mix 4 tbsp sea snail broth, 2 tbsp soy sauce, 2 tbsp vinegar, 1 tbsp corn syrup, 0.5 tbsp minced garlic, and a small amount of mustard in a bowl.

Combine the sea snails, sliced vegetables, and seasoning mixture in the bowl. Toss well to coat evenly.