In a large skillet (mine is 11" cast iron), heat up olive oil and butter over medium heat.
Season chicken thighs with salt and pepper and oregano.
Place chicken skin-side down in pan. Cook for 4 to 5 minutes.
Flip chicken over, cook for 5 more minutes.
Add garlic, soy sauce and lemon juice to pan.
Place onion rings and lemon slices over chicken.
Place skillet in oven. Roast for 25 minutes OR until the internal temperature of each thigh is 165 to 175 degrees F. Spoon the pan juices over chicken half way through roasting.
Remove from oven and let sit 10 minutes before serving. Drizzle pan sauce over chicken and serve.
Notes
I used 4 large thighs (see photos), you can use 5 smaller chicken thighs for this recipe.