Step 1: Prepare the Puff Pastry Tart

1. Prepare the ingredients:
   • Preheat the oven to 180°C (350°F).
   • On a lightly floured surface, roll out the puff pastry if needed to fit your baking tray.
2. Prepare the puff pastry:
   • Place the puff pastry on a baking tray lined with parchment paper.
   • Brush the 20g melted butter over the surface of the puff pastry.
3. Add toppings:
   • Spread 30g tomato sauce evenly over the puff pastry, leaving a small border around the edges.
   • Evenly distribute the chopped ham and halved cherry tomatoes over the tomato sauce.
   • Sprinkle with 3g salt, 3g black pepper, and 3g oregano.
   • Top with 100g grated mozzarella cheese.
4. Bake the tart:
   • Place the tart in the preheated oven and bake for 20 minutes over medium heat, or until the puff pastry is golden brown and the cheese is melted and bubbly.

Step 2: Prepare the Greek Yogurt Mustard Sauce

1. In a small bowl, combine 100g Greek yogurt, 15g mustard, 15g ketchup, 3g oregano, 3g black pepper, and 3g salt.
2. Mix well until all ingredients are fully combined. Set aside.

Step 3: Serve

• Remove the tart from the oven and let it cool slightly before slicing.
• Serve slices of the Ham and Cherry Tomato Puff Pastry Tart with a dollop of the Greek yogurt mustard sauce on the side.