Cook Rice: Combine 150g rice, 300g water, and a pinch of salt in a pot. Bring to a boil, reduce heat to low, and simmer covered for 10 minutes. Turn off heat and let rest for 10 minutes.
Make Tofu: Prepare gochujang tofu according to the recipe linked in the main post.
Prep Vegetables: While tofu and rice cooks, thinly slice onion and massage with half the rice vinegar and salt. Slice radish and cucumber, then combine with remaining vinegar, salt, and most of the shichimi togarashi.
Cook Pak Choi: Steam or boil pak choi for 3-4 minutes until slightly softened. Thinly slice spring onion.
Assemble Bowls: Layer rice, pak choi, pickled radish/cucumber, and onion (drained and mixed with mayonnaise) in bowls.
Garnish and Serve: Top with spring onion, sesame seeds, and remaining shichimi togarashi.