Cut chicken legs and breasts into two pieces each and make deep crossway slits to the bone.
Rub salt and lemon juice into the chicken pieces and set aside for 20 minutes.
Blend onion, garlic, ginger, chillies, garam masala, and a spoonful of yoghurt until smooth.
Mix the blended spice paste with the remaining yoghurt.
Coat chicken in the marinade, cover, and refrigerate for 6 to 24 hours.
Preheat the oven to its maximum temperature and arrange a shelf in the top third.
Place chicken on a baking tray in a single layer, discarding excess marinade.
Roast for 20-25 minutes, removing breast pieces earlier if they are cooked through.
Transfer chicken to a serving plate and serve with fresh citrus wedges.