In a medium pan, heat olive oil over medium-high heat. Sauté spinach, tossing until wilted. Transfer to a plate.
Warm pita pockets in the microwave until soft and pliable. Open the pita pockets and spread with pesto. Top with feta, chopped sun dried tomatoes and spinach. Add sliced mozzarella on top.
Grill pita in a contact grill or panini press for 4 minutes or until mozzarella is melted and pita develops nice char marks. Serve hot.