Heat pan (NO FATS!). In the meantime, only remove skin from chicken thighs and season with salt and pepper. When hot enough, add the chicken to the pan and allow to brown - the seasoning helps crisp the meat.
When browned, drizzle in the oil and add the onions. Let them cook. When the onions have cooked for about 10 minutes, add a generous glug of wine - I usually add about half bottle for 4 thighs.
Cover the pan and cook slowly for about half and hour. Add a knob of butter - this will give the sauce a lovely glaze.