Luke's Kitchen's 'neverfail' fish pizza

Ingredients

• Base sauce
• 1 tbsp olive oil
• 1 onion, diced
• 1 sprig rosemary
• 2 tbsp tomato paste
• 2 cloves garlic
• 2 tins whole tomatoes
• salt and pepper
• Garlic oil (for seasoning fish)
• 1 clove garlic
• 2 tbsp olive oil
• Pizza
• fresh fish, cut into thin strips no more than 1cm wide
• red onion, finely sliced
• courgette, finely sliced
• mushrooms, finely sliced
• handful of fresh rocket
• mozzarella
• lemon wedge
• garlic aioli