Slice the pork tenderloin into very thin, bite-sized strips to mimic the texture of pork belly while keeping the meal lean.
In a small bowl, whisk together the gochujang, coconut aminos, grated ginger, and minced garlic until smooth.
Heat the toasted sesame oil in a large cast-iron skillet over medium-high heat until it begins to shimmer.
Season the pork strips with sea salt and black pepper, then add them to the hot skillet in a single layer.
Sear the pork for 2 to 3 minutes per side without crowding the pan until the edges are deeply browned and caramelized.
Pour the gochujang sauce mixture over the pork and toss for 1 minute until the sauce reduces into a sticky, glossy glaze.
Remove the pork from the pan and quickly sauté the baby bok choy in the remaining glaze for 2 minutes until the leaves wilt.
Assemble the bowl by placing the cooked brown rice at the base, topping with the glazed pork and bok choy.
Garnish the bowl with sliced scallions and toasted sesame seeds before serving hot.