Pork loin with Parma ham and oregano

INGREDIENTS

• 1.5kg/3lb 5oz boneless and rindless loin of pork
• 2 fat cloves garlic
• few sprigs fresh oregano
• 100g/3½oz Parma ham, sliced
• ⅓ tsp dried chilli
• 1 onion or 2 shallots
• 2 tbsp olive oil
• 4 tbsp dry white vermouth
• 4 tbsp boiling water