Preheat oven to 180ºC/350ºF. Line a baking sheet with baking paper and set aside.

Prepare the Spicy Chilli Oil by placing the oil and the dry red chili in a small saucepan, and bring to boil for one minute. After that, remove from heat and let cool to room temperature. Store in an airtight bottle or jar. 

Unfold the puff pastry and place it onto prepared baking sheet. 

Use a sharp knife to score the perimeter of the dough 1-inch from the edge, making sure not to cut all the way through the dough. Prick pastry in a few places with a fork inside the scored rectangle so that the center of the pastry does not puff in the oven.

Spread the cream cheese on the pastry, arrange the sliced leeks and the halved tomatoes over the cheese. Drizzle everything with spicy chili oil, around 2 tablespoons, and sprinkle with salt and pepper.

Bake in oven for 15 minutes or until the edges of pastry are browned, puffed, and crisp. Let tart cool 10 minutes before cutting into pieces.