Matsyangasana is the ultimate open twist and one of the few twists that addresses all parts of the spine as well as the hips and shoulders.
Inhaling, lift the bottom of the belly, lengthen the side waists, and press the right knee into the floor. Exhaling, press down into the hands and twist the spine, moving the right hip towards the left knee.
Work the rhythm of the twist: inhaling, lift; exhaling, twist. Keep your arms straight and as you exhale and twist, lift the left shoulder up and drop the right one down. Hold for three breaths.
Inhaling, release from the twist and walk the hands back around to the front to come out of the pose. Bring the legs back into Baddha Konasana.
Change sides. Repeat the pose on both sides as many times as you like. Work with feeling not force to twist the entire spine, not just the parts that like to twist easily.