After bracing, and leaning back just enough to find a balance point, take the kettlebell “by the horns” (hands close to the base, attached forcefully to the handle), and lift/ move it from side-to-side, twisting the trunk, and touching the ground on each. L + R, in our vernacular, = 1 rep.
There are many versions of the “Russian Twist” in circulation. We choose to limitedly use this one, because it requires an extreme amount of engagement and control to perform properly, and its simplicity and difficulty make it a valuable accessory.