Heat vegetable oil over medium-heat in a large skillet. Season chicken thighs on both sides with thyme, oregano, salt, and pepper. Place thighs, skin-side down, into the hot skillet and cook until browned, about 8 minutes. Flip thighs over and brown other side, an additional 8 minutes. Remove thighs from skillet onto a large plate, and set aside. Reduce heat to medium-low.