Pork belly with cider and rosemary

Ingredients

• 2 tablespoons rosemary, chop
• Pound to a rough paste
• 3 cloves, chop
• 1 teaspoon salt
• 1 tablespoon muscovado sugar
• 2 tablespoons olive oil
• 1 orange's zest
• 1 lemon's zest
• 2kg pork belly
• 500ml cider, liquid
• 600ml chicken stock, hot
• several sprigs rosemary
• 1 orange's juice
• 1 lemon's juice
• 2 tablespoons muscovado sugar
• 1 tablespoon flour
• 25g butter