This is probably the easiest variation we have to offer. It's just a hip-length tunic with side vents.
Cut out the simple blouse lengthening the body 5". Surge the sides of the front and back pieces.
Stitch the side seams stopping 6" from the bottom edge.
Top stitch the vent. Be sure to have a bar tack at the top of the vent to ensure security. Hem the bottom regularly.