In a medium bowl, combine egg, milk, flour, oil, and salt. Beat until combined. Heat a lightly greased 6-inch nonstick skillet over medium heat.
Remove from heat. Spoon in 2 tablespoons batter, lift and tilt skillet to spread batter.
Return to heat, brown on one side only. (Or cook on a crepe maker according to manufacturer's directions.) Invert skillet over paper towels, remove crepe. Repeat with remaining batter, greasing skillet occasionally.
To make Peanut Butter Dip: In a blender container or food processor bowl, add peanut butter, sour cream, milk, and vanilla. Cover and blend.
Spread Peanut Butter Dip down center of each crepe. Top with Banana slices. Fold sides of crepes up over bananas.