Supported half lotus

Technique

Sitting with legs extended, bend the left knee and bring the left foot to rest on top of the upper right thigh with the sole of the foot facing upward (Half Lotus).
Bend the right knee and bring the right foot back to place it near the right hip bone (as in Sitting bound one-leg forward fold) without letting the right knee drop over to the right, or the lotus foot slide out.
Bring one or both hands behind the hips to help you fold forward.
If possible, take one or both hands forward to reach into the forward fold.
Take 5 breaths.
Then unfold and repeat on the other side - right leg in half lotus and left leg bent with the foot flat.

This is an external rotation for the hip that is in half lotus, and an internal rotation for the bent leg with the foot down.
Tuck the half lotus foot securely into the hip crease before bending the other leg. Only bend that leg as far as is comfortable for the lotus ankle, knee and hip.
You’re trying to come forward enough that the foot and opposite thigh are the foundation of the posture, which means the lotus leg has to rotate externally even more. If it won’t go, DO NOT FORCE IT. This will put pressure on the knee rather than the hip, and potentially cause pain or harm.
Keep the spine tall and focus on hinging at the hip rather than rounding the spine to go forward.