Place the chicken pieces in a large bowl and mix in the olive oil, crushed garlic and sage. Cover and leave to marinate in the fridge for 1 hour or ideally overnight.
Heat 1tbsp of the oil in a large frying pan, season the chicken and fry in batches until browned all over. Leave the chicken skin-side up and add the whole garlic cloves, vinegar, stock, lemon zest and olives. You want the chicken in a single layer, and don’t cover it. Bring to the boil then simmer for 1 hour.
To serve, heat the remaining oil in a small frying pan over a medium heat and fry some sage leaves in batches for a few seconds until crisp. Set aside on kitchen towel until ready to serve. This is delicious with new potatoes or bread.
COOK'S TIP Buy olives in oil, not brine. Some olives can be over salty, which will be too overpowering for the dish. Taste before you buy if you can.