Mix flour, salt and pepper on a plate or pie pan. Pat chicken dry then dip in flour mixture to coat.
Melt 3 tablespoons butter in a large frying pan. Add the cutlets and fry until golden, about 3 minutes, then turn over. Add remaining butter and the lemon and lemon juice. Cook until cooked through and golden on the second side too.
Add the stock or wine to the pan and stir making sure to pull up any browned bits. Simmer until just thickened, being careful not to reduce the sauce too much (if that happens stir in some water to reconstitute it)
Sprinkle with parsley and re-salt lightly before serving (the re-salting was surprisingly important to the final flavor). Add a slice of lemon if desired. Top with a spoonful of pan juices as you serve.
I am not a health professional and nutrition data is calculated programatically. Accuracy may vary with product selection, calculator accuracy, etc. Consult a professional for the best information.