In a small bowl, combine gochujang, soy sauce, minced ginger, minced garlic, and caster sugar. Whisk together and set aside.
Slice the chicken thighs into bite-sized, forkable chunks.
Heat a thin film of neutral oil in a large frying pan over medium-high heat until it shimmers.
Add the chicken pieces in a single layer and cook without moving for about 5 minutes, until well browned on one side.
Turn the chicken pieces and reduce the heat slightly. Cook for an additional 2 minutes.
Pour the prepared sauce over the chicken. Add any quick-cooking vegetables if desired.
Continue cooking for 2 more minutes, occasionally stirring to coat the chicken as the sauce thickens.
If the sauce thickens too quickly, add a splash of water to extend cooking time.
Check that the chicken is cooked through by cutting into a piece and serve hot over sushi rice or hokkien noodles.
