Dry chicken really well with paper towels. Loosen the skin from the thighs and divide the tablespoon of Dijon between the four thighs, spreading the Dijon under the skin. Generously salt and pepper both sides of thighs.
Drizzle olive oil in a sauté pan and heat over medium high heat. When oil is shimmering and very hot, place thighs in pan, skin side down. Don’t move or shift thighs once you set them down. Let cook for about 12-15 minutes, lowering heat to medium halfway through the cooking time.
Flip thighs over and add onions to the pan. Cook for an additional 12-15 minutes, stirring occasionally to shift the onions around. Cook until thighs reach 165º, lowering or raising heat as needed to keep chicken cooking but no burn the onions.
Whisk sour cream, half and half, Dijon and wine together.
Remove chicken to a side plate and add sour cream mixture to onions in sauté pan. Cook, whisking occasionally, over medium low heat, for 1-2 minutes. Return chicken to pan and spoon sauce over tops of chicken thighs. Serve right away.
