Preheat oven to 425 degrees. Line a baking sheet with parchment paper.

Unfold and flatten the puff pasty, then cut into circles using a a cookie cutter or the edge of a round glass. Place on the baking sheet.

In a small bowl, whisk together the egg and water, then brush the tops of the puff pastry with the mixture. Place a tomato on top of each puff pastry, then add a dollop of goat cheese, a few shreds of fresh basil and a sprinkling of salt and pepper. Bake for 15-20 minutes, or until the pastry is puffy and golden brown and the cheese is melted and golden. Allow to cool for a few minutes, then drizzle with the balsamic reduction and serve.