Soak 1 tbsp dried wakame seaweed in a bowl of warm water according to the instructions on the packaging. (This usually takes 5-10 mins).
Wrap 150 g silken tofu in kitchen paper and microwave it for 1 minute 30 seconds at 600W. Allow it to cool slightly before cutting it into bitesize cubes.
Mix the dressing ingredients (1 tbsp dashi stock, 1 tbsp rice vinegar, 1 ½ tbsp Japanese soy sauce (koikuchi shoyu), ¼ tsp sugar, 1 tbsp toasted sesame oil, 1 tsp ginger paste and ½ tsp ground sesame seeds) in a small bowl or jug.
Drain the water from the wakame and squeeze it thoroughly to remove any excess water. Add it to a large mixing bowl along with 50 g Japanese cucumber, 5 mini tomatoes and cubed tofu. Add the dressing and mix until well distributed. (Mix gently to avoid breaking the tofu too much. Alternatively, mix without the tofu and add it at the end.)Cover the bowl and chill in the fridge for 20-30 minutes before serving.
Divide into serving bowls, sprinkle with bonito flakes (katsuobushi) and enjoy!