Grind garlic with mortar and pestle until becoming a paste. You can use an electric spice grinder if you don’t have mortar and pestle.
Place chicken wings into a bowl, then add garlic paste, fish sauce, vinegar, and black pepper. Mix well. Marinate for 4 hours in the refrigerator.
Grind ginger with mortar and pestle until becoming a paste. Place the ginger paste into a small bowl then add 3 tbsp water. Set aside.
In a big bowl, mix flour, cornstarch, and a pinch of salt and stir to combine.
Coat the chicken wings with a flour mixture.
Then fry the chicken wings at 350°F/170°C until golden brown and crispy. Set aside and let cool on a cooling rack.
For the spicy BBQ sauce, crush bird's eye chilis with pestle and mortar.
In a pan, heat 3 tbsp oil then saute the onions for 2 minutes.
Add bird's eye chili paste, BBQ sauce, ketchup, oyster sauce, and ginger water. Stir to combine.
Coat the fried chicken wings with the spicy BBQ sauce.
Spicy BBQ chicken wings are ready to serve!