In this 55th verse of Vigyana Bhairava Tantra, Shiva says:
Seated comfortably in a soft seat
On one buttock with hands and legs relaxed
Bihar School Of Yoga recommends ardha matsyendrasana, shown here and dhyana veerasana as fitting Shiva’s description.
Rather than the asana or posture itself, i would like to focus on the intent. In the Patanjali Yoga Sutra, Patanjali defines asana or body posture as one that is form and comfortable, that is all. All the contortions that followed came through other practitioner manuals.
Let the mind transcend to Shiva