How do I use the surface normal to convert it into a roll for an object? I want to make an object parallel to the tangent it is on

Suppose the object is firing a raycast down on a sphere.

The object is facing forward.
The raycast is fired in the -y direction of the object so it goes downwards to hit the sphere.

The resulting perpendicular to the tangent is what I want to be used to give that object some roll which is parallel to the tangent.

Please help!

You mean this?