Healthy gravy - Good Food Middle East

Ingredients

• 1 tsp sunflower oil
• 1 large onion, chopped
• 3 large carrots, chopped
• 1 tbsp ketchup
• handful dried porcini mushrooms
• 3 tbsp balsamic vinegar
• 1l low-salt vegetable stock, or chicken stock if not making it vegetarian
• 1 tbsp cornflour