Pollo alla cacciatora or chicken cacciatore is typical Tuscan dish, traditionally cooked in a terracotta pot with caramelised onions, capers, olives, tomatoes and herbs. As final touch fried potatoes are added to the pot, too.
Blanch the olives in boiling water with the celery for a few seconds. Drain well.
Place onions in a saucepan with the sugar, a pinch of salt and 1/2 glass of water. Cook over medium heat, covered, until the onions cook down and partially caramelise, about 30 minutes. Stir from time to time.
Brown the chicken in a frying pan with a drizzle of oil. Transfer to a terracotta pot (or casserole) and add the blanched olives and celery along with the caramelised onions, tomatoes, lemon juice, capers, basil, salt and pepper. Cook covered over medium heat until the chicken is cooked through (the centre of the leg is not pink anymore), about 1 hour.
In the meantime deep fry the potatoes in olive oil. Add the potatoes to the pot a few minutes before the removing from heat.