For the chicken “marinade,” combine the onion, garlic, salt, pepper, sugar, and MSG into a medium mixing bowl. Add the vinegar and stir well, making sure sugar completely dissolves.
Place the chicken pieces into a large zip-lock type baggie or a non-metallic bowl. Pour the vinegar mixture over the chicken. Allow chicken to marinate for at least 6 hours, but preferably overnight, in the refrigerator. If using a baggie, turn it once or twice to assure the marinade permeates the meat evenly.
When ready to fry the chicken, combine the flour dredging ingredients in a bowl or zip-lock type baggie; combine well.
Drain the chicken into a colander, discarding the liquid and most of the garlic and onion pieces.
In a deep/heavy frypan (or deep fryer), heat the oil to 325 degrees F.
Place chicken pieces into the flour mixture and toss to coat well. Slowly place the coated chicken into the hot oil and fry for 15 – 20 minutes, depending on the size and thickness of the chicken pieces.
Turn the chicken once or twice for even browning; drain on paper towel before serving.