Pat the chicken breasts with a paper towel to remove moisture.  Carefully slice the chicken breasts horizontally to create 4 cutlets.  Season both sides generously with salt and pepper, place on a plate and reserve. Do not pound/flatten the cutlets.

Measure the bread crumbs into a second shallow bowl.

Crack the egg into a medium-size shallow bowl and whisk it with a fork to break it up.  Add the sour cream, Dijon mustard, chives and flour.  Stir together until smooth.

With a fork or tongs, dip a chicken cutlet into the bowl of wet mixture, turning to coat both sides.  Lift it into the dish of bread crumbs, pressing down with the back of the fork.  Turn the cutlet to the opposite side and spoon bread crumbs over the top, also pressing to allow the crumbs to adhere.  

Lift the breaded cutlet and place on a plate and continue the process with the remaining cutlets.  

Set the plate of cutlets in the refrigerator for 30 minutes. 

Heat an 8-inch cast iron or stainless steel skillet over medium-high heat, add 2 tablespoons of the oil and when it is hot place 2 of the cutlets into the skillet.  

Cook the cutlets for 4 minutes until golden brown, flip them over and cook for an additional 3 minutes.  Transfer the cutlets to a paper towel-lined plate.  Add the remaining 2 tablespoons of oil and when it is hot, repeat the process with the additional chicken cutlets.

Transfer the cooked cutlets to a serving platter.  Garnish the cutlets with chopped chives and lemon wedges and serve a small dish of sour cream along side.