Cut the chicken fillet into bite-sized cubes. In a food processor, combine garlic, soy sauce, fish sauce, chicken powder, pepper, mushroom powder, and melted butter. Process until smooth.
Place the chicken cubes in a bowl and pour in the blended marinade. Mix well until all pieces are evenly coated. Cover and refrigerate for at least 30 minutes or overnight for deeper flavor.
Once the chicken has marinated, thread 3–4 pieces onto each skewer. Arrange them on a tray and set aside. Heat a grilling pan over medium heat and lightly spray with oil. Place the chicken satay on the pan and grill on one side.
Flip and grill the satay on both sides until cooked through and lightly charred. Spray with coconut oil as needed to prevent sticking. Transfer the sate taichan to a serving plate.
In a food processor, blend chilies, garlic, chicken powder, coconut oil, sugar, and water until smooth. Transfer the mixture to a small pan and bring it to a gentle simmer.
Remove from the heat and let it cool slightly before transferring to a serving bowl. Squeeze fresh lime juice into the sambal before serving.
Serve the sate taichan with the sambal, a pinch of salt, and lime wedges on the side.
Notes
Marinate longer for deeper flavor - Thirty minutes works well, but marinating overnight allows the seasonings to penetrate the chicken and gives a richer flavor.
Keep the chicken pieces similar in size - Try cutting the chicken into similar bite-sized pieces so they cook evenly and finish grilling at the same time.
Do not pack the skewers too tightly - Leave a small space between the chicken pieces so heat can circulate properly and create lightly charred edges.
Cook over medium heat - Cooking over very high heat may burn the outside before the chicken cooks through. Medium heat allows the chicken to stay juicy while developing a smoky char.
Lightly oil the pan while grilling - Spraying or brushing a little oil on the pan helps prevent sticking and keeps the satay from drying out.
Adjust the sambal to your spice level - Reduce the number of bird's eye chilies for a milder sauce, or add more if you love extra heat.
Serve with fresh lime and a pinch of salt - Fresh lime juice and a little salt are part of what makes Sate Taichan unique. They brighten the flavor and balance the smoky grilled chicken.