Spanish Chicken with Chorizo and Potatoes

Ingredients

• 3 tablespoons regular olive oil
• 12 chicken thighs or drumsticks (bone in, with skin)
• 1 3/4 lbs Spanish chorizo sausages, whole if baby ones, or cut into 4-cm chunks if regular-sized
• 2 1/4 lbs baby potatoes, half the larger ones
• 2 red onions, peeled and roughly chopped
• 2 teaspoons dried oregano
• grated zest of one orange
• salt to taste