2.Soak saffron in the hot water in small heatproof bowl.
3.Meanwhile, peel onions, leaving root ends intact. Heat oil in 4-litre (16-cup) flameproof dish; cook onions, covered, stirring occasionally, over low heat until browned lightly. Add garlic, potato, chilli and spices; cook, stirring, 1 minute. Add saffron mixture, tomato and wine; bring to the boil, season. Cover; cook, in oven, 30 minutes.
4.Add chicken to dish; spoon some of the pan juices over chicken, cover; cook, in oven, 2 hours.
5.Meanwhile, make fetta sauce. Blend or process ingredients until smooth; season to taste.
6.Discard chillies from dish. Serve chicken mixture drizzled with fetta sauce; sprinkle with coriander.
Fetta sauce also makes an excellent accompaniment to slow-roasted lamb. To peel baby onions, pour boiling water over them in a heatproof bowl; stand 5 minutes, then the skins should just fall off.