Cut the tofu into blocks around 2cm (¾") squared, and 7.5cm (3") long, you should have 6.
Cut the pak choi in half lengthways.
Slice the spring onions thinly (2-3mm or ⅛" thick) at a 45-degree angle to the stem.
Cut the red chilli in half lengthways and then remove the seeds before shredding as finely as you can.
Mix together the soy sauces, rice wine, brown sugar, and garlic powder.
Add 1cm (½") of oil to a 30cm or 12" skillet or frying pan and heat to 170°C or 340°F.
Just before the oil reaches temperature, roll the strips of tofu around in the cornflour, then tap off any excess and then carefully place in the oil.Fry until golden on all sides, which should take 7-8 minutes in total, then remove from the oil and place on a kitchen towel to drain.
Drain the oil from the pan except for a scant coating and return it to a medium-high heat.
When hot placed the pak choi in the pan, cut side down and fry for 3 minutes, then flip and cook for another 2 minutes.
Add the tofu and shredded chilli to the pan and then pour over our teriyaki sauce.
Cook for 1-2 more minutes, stirring constantly.
Serve drizzled with a little good quality toasted sesame oil.