Preheat the oven to 'keep warm'. Place a wire rack on a baking sheet. Make the cucumber salad - see below and store in the fridge until ready to serve. It can be made an hour or two ahead of serving.
Combine flour, salt & pepper in a medium shallow dish. Toss the chicken pieces in flour until well coated, shaking to remove excess flour.
Lightly cover the bottom of a large frying pan with some oil. Cook the chicken in 2 to 3 batches on medium to medium-high heat until golden & crisp, about 4 to 5 minutes per side. Transfer to the wire rack & place in the oven to keep warm while you keep cooking the remaining chicken, adding a little more oil to the pan if needed. When the chicken is cooked, wipe the pan clean.
Combine the teriyaki sauce, chili sauce and vinegar in a small bowl. Stir the sauce and add the same frying pan. Bring to a simmer on medium. Simmer, uncovered, for a minute until the sauce is starting to thicken slightly. Add the chicken and stir or gently toss until coated in the sauce and glazed.