Combine cornstarch and water in a small bowl, stirring well.
Combine banana, 1 tablespoon caramel topping, and cinnamon in a small bowl, stirring well. Working with 1 wonton wrapper at a time (cover remaining wrappers with a damp towel to keep from drying), moisten edges of each wonton wrapper with cornstarch mixture. Place about 2 teaspoons banana mixture in center of each wrapper; fold in half to close, forming a rectangle. Press edges to seal.
Heat 4 teaspoons oil in a large nonstick skillet over medium-high heat. Place 6 pockets in pan; cook 3 to 4 minutes on each side or until golden. Remove from pan, and cool on a wire rack. Repeat procedure with remaining oil and pockets. Dust with powdered sugar; serve with remaining 3 tablespoons caramel topping.