Cut cod into manageable pieces and process in food processor until it becomes a fine paste

Process peeled shrimp in food processor until it becomes a fine paste

Combine fish and shrimp paste with garlic chives, ginger, cornstarch, lard, salt, sugar, MSG, white pepper, and sesame oil

Mix the paste thoroughly until well combined and tacky

Spread the paste into a flat even layer and freeze until set

Prepare ginger-scallion sauce by blitzing scallions, ginger, garlic, and long green chilies in food processor

Season the ginger-scallion mixture with salt and MSG

Heat ¼ cup neutral oil to 400°F and pour over the aromatics to cook them

Cool the ginger-scallion mixture and fold in pickled mustard greens

Make tartar sauce by combining mayo with strained ginger-scallion mixture, pickles, lemon zest and juice, cilantro, salt, and MSG

Portion frozen fish paste into 10 patties (approximately 2x5 inches)

Set up breading station with cornstarch, beaten eggs, and panko breadcrumbs

Bread patties by coating in cornstarch, then egg, then panko

Fry breaded patties in oil until golden brown (about 4 minutes)

Toast potato rolls with mayo until golden but still squishy

Place full slice of American cheese on bottom of toasted bun

Place hot fried patty on top of cheese

Top with generous amount of ginger-scallion tartar sauce

Close sandwich with top bun and serve in clamshell box