Pepperoni Pizza

Ingredients

• 1 tsp extra-light olive oil
• 140 g button mushrooms (trimmed and sliced)
• 1 large onion (cut into thin wedges)
• 2 garlic cloves (crushed)
• 2 tsp fresh oregano (or 1 teaspoon dried oregano)
• 4 Italian tomatoes (sliced)
• 2 tsp balsamic vinegar
• 1 ready-made thick pizza base (about 300 g)
• 3/4 cup no-salt-added tomato paste
• 30 g pepperoni ((about 16 slices))
• 1 cup reduced-fat mozzarella cheese (grated)
• 4 tbsp parsley (chopped, to sprinkle)