The "plowhandle" single-action grips were designed that way for two reasons:
To let the gun roll up in recoil ILO back into the shooter's hand, and
To let the gun rotate up so as to place the hammer spur under the thumb of the shooting hand to enable a rapid second, etc, shot(s).
The proper grip for one would be to allow the small finger of the shooting hand to curl under the bottom of the grip/frame.
That finger would then have the leverage to help pull the gun back down out of recoil as the thumb cocks the revolver and the eyes align for the subsequent shot(s).
If your SA recoils harder than a .357, then do the same thing - but wrap the non-shooting hand around the front of the shooting hand's fingers, below the trigger guard.
It's also somewhat easier to cock the hammer with the thumb of the non-shooting hand, when using the two-handed method.