This dish was on the first-class dinner menu of the Titanic, according to the book, "Last Dinner on the Titanic" (Hyperion/Madison Press). It is much better with fresh thyme if it is available.
In a plastic bag, shake together the flour, 1 tablespoon thyme (1/2 teaspoon if using dried), salt and pepper.
One at a time, dip chicken breasts into the egg, and then shake in flour mixture.
In a large deep skillet, heat 2 tablespoons of the vegetable oil over medium-high heat.
Place chicken in pan, skin side down.
Cook, turning once, for 10 minutes or until golden brown.
Remove from skillet and place chicken in 225°F oven to keep warm.
Reduce heat to medium; add remaining oil to skillet.
Stir in onions, garlic and remaining thyme.
Cook, stirring often, for 5 minutes or until onions are translucent.
Increase heat to medium-high and continue to cook onions, stirring often, for 5 more minutes or until golden brown.
Add wine to pan.
Cook, stirring to scrape up any brown bits, for about 1 minute or until reduced by half.
Stir in stock, tomato paste and sugar.
Boil for 2 minutes or until mixture begins to thicken.
Return chicken to pan, turning to coat.
Cook for 5 minutes or until juices from chicken run clear.
*To make cutlets, cut chicken breast into 2-3 pieces of approximately equal size. Cover with plastic wrap and gently pound to even 1/2-inch thickness. Cutlets cook more evenly and are more tender than a whole breast piece.