1. Sprinkle chicken with salt and pepper (¼ tsp each). Heat olive oil in a frying pan. Fry chicken until cooked through (10-15 minutes), turning once. Transfer to a plate. Keep warm.
2. Pour the wine into the heated frying pan. Boil for about 1 minute until the liquid has evaporated by half. Stir in sour cream, mustard and tarragon. Cook, stirring, about 2 minutes.
3. Pour the resulting chicken juice into the sauce. Before serving, pour the sauce over the chicken breasts. Bon appetit!