Step 1: Preheat your oven to 375°F (190°C). Lay out the thawed puff pastry sheet on a lightly floured surface or parchment paper. Using a sharp knife or pizza cutter, cut the pastry into even triangles.
Step 2: In a small bowl, combine the mango puree, chili powder, and lemon zest. Spread a thin, even layer of this mango mixture onto each puff pastry triangle, leaving a small border around the edges.
Step 3: Brush the exposed edges of the pastry triangles with the beaten egg wash. Carefully transfer the triangles to a baking sheet lined with parchment paper. Bake for 12-15 minutes, or until the pastry is puffed, golden, and crispy.
Step 4: Once out of the oven, immediately garnish the warm triangles with chopped fresh cilantro and crumbled feta cheese. Arrange fresh mango slices, lemon wedges, and mint leaves alongside for accompaniment. Serve these delightful treats warm or at room temperature and enjoy!