Cut the pineapple into ½-inch thick slices.
Cut the chicken breast into ½-inch thick slices. Cut in half lengthwise into strips, rotate and cut again into 1-inch chunks.
In a bowl, add the flour, cornstarch and baking powder. Add the water a bit at a time until you reach the desired consistency. Mix the batter until no lumps remain.
In a small bowl, mix together the ketchup, red vinegar, rice vinegar, salt and sugar until fully combined.
In a small bowl, mix together the potato starch and water until thoroughly combined.
Heat a wok on high, about 1 minute.
Add the sauce to the wok. Turn the heat to high.
