Jaccard each chicken breast ~10 times per side (or poke 20–30 times per side with a sharp fork). Slice each breast into 3–4 long strips, then cut into ~¾in cubes.

In a medium bowl combine soy sauce, mirin, MSG, baking soda, and potato starch. Add chicken and mix to coat. Rest 20 min.

In a large bowl whisk flour, baking powder, garlic powder, salt, and potato starch until uniform.

Weigh 250g of the dry mix into a separate bowl. Add 300g water and stir until it looks like thin pancake batter.

Pour 200g of the batter into the remaining dry mix. Briefly whisk, then use your hand to rub and crumble until you've got rice-to-lentil sized pebbles with a powdery background.

Toss about ⅓ of the marinated chicken in the batter bowl to lightly coat. Lift, let excess drip, then drop into the craggy dry mix. Fluff/tumble to build a strong base layer. For each piece, shower on extra craggy bits and give a soft squeeze, then shake off excess. Repeat with remaining chicken.

Spread breaded chicken on a sheet tray and refrigerate 20 min.

In a bowl whisk soy sauce, sesame oil, mirin, rice vinegar, sambal, ketchup, sugar, brown sugar, cornstarch, and MSG until smooth.

Heat neutral oil in a Dutch oven to about 325°F (1.5–2in depth). Fry chicken in two batches. Gently lower in, don't touch for 1 minute, then nudge to prevent sticking. Fry 6–7 min until deeply golden. Drain on a rack or paper towel. Repeat with second batch.

Heat a wok or large nonstick pan over high. Add a squeeze of oil, then scallions; stir-fry 60 sec. Add cracked chiles and toast briefly. Add ginger and garlic; stir constantly 30–40 sec until just fragrant.

Pour in the sauce around the hot pan edge. Bring to a boil and reduce 15–20% until it leaves a trail. Add fried chicken and toss ~30 sec to simmer in the sauce.

Pile over steamed rice. Spoon on any extra sauce from the wok. Garnish with reserved scallion greens.