Start position: Begin on your hands an knees in a tabletop position. Simply being in this position adds a posterior glide of the head of the femur.
The movement: place one foot over the other leg which will put your hip into slight external rotation. and at this point rock back until you feel a good mobilization of this hip. you essentially want to shift your weight/hip over the hip you want to mobilize. This exercise will require much less external rotation than a pigeon pose, a pigeon pose will target the piriformis; however, with less external rotation this will target the posterior hip capsule.
Note: You should only feel a deep stretching sensation in the back of your hip, if you feel it in the front of your hip, you either need to change your foot position (most likely putting your hip in external rotation and moving foot closer/on top of your other foot) or you need to perform a banded Hip Banded Distraction