Place the toasted sesame oil in a pot and sweat the garlic and ginger over medium heat.
Add the soy sauce, rice wine vinegar, yuzu juice, brown sugar, and gochujang. Bring to a simmer.
Combine the cornstarch and water to make a slurry. Slowly whisk the slurry into the simmering sauce, ensuring there are no clumps. Bring back to a simmer to thicken.
Turn heat off and cool the sauce down.
Once cool, whisk in the sliced scallions.
Store refrigerated in an airtight container until use.