Cod With Tomato And Thyme

Ingredients

• 1 3/4 lbs medium-sized potatoes, scrubbed
• 1 tbsp sunflower oil
• 1 None onion, peeled and chopped
• 1 None garlic clove, peeled and chopped
• 1 None celery stalk, chopped
• 1 1/3 lb tomato, quartered, deseeded and diced
• 1/2 tbsp sugar
• 1 tbsp fresh thyme leaves, plus extra sprigs to garnish
• 1 tbsp Worcestershire sauce
• 3 tbsp butter
• 4 None cod fillets (each about 5 oz)