Pound the chicken breast to ¼-inch thickness. I like to cover the chicken with plastic wrap and use a meat tenderizer hammer to flatten it.
Cut the flattened chicken breast into 4 pieces.
Heat 1½ teaspoons of olive oil in a skillet over medium heat.
In a shallow bowl, stir together the flour, onion powder, thyme pepper, and salt. . While your skillet is heating up, dredge the 4 pieces of chicken in the flour mixture. Make sure you coat the whole piece of chicken, and shake off any extra flour.
You'll probably need to cook the chicken in 2 batches. If you overfill your skillet, the chicken will just stew and you won't get a crispy coating. Cook 2 pieces of chicken in the olive oil, about 2 to 3 minutes per side.
The chicken is done when lightly browned on the outside and 165 °F on the inside.
Transfer the first batch of chicken to a plate.
Add 1½ more teaspoons of olive oil to the skillet. Cook the other 2 pieces of chicken.
Transfer the second back of chicken to a plate when it's done.
Add the onion, garlic and chicken stock to the same skillet and cook for about 3 minutes, scraping up any browned bits stuck to the bottom of the pan.
Add 2 tablespoon of wine and cook for 1 more minute.
Stir in the lemon juice and the capers.
Return the chicken to the skillet and spoon the sauce over the chicken. Put the cover on the skillet and bring the sauce to a boil over medium heat. Reduce heat to low and simmer, covered, for 5 more minutes.
Spoon the sauce over the chicken to serve.