Ride alongside the obstacle, with your wheel parallel to the step
1° Star in balance with your free hand on the side you want to climb, to search momentum sideways as well as to secure the move.
2° Launch a pre-load hop and tuck in the air, pulling the unicycle under you to prepare for a firm stomp, flat on both pedals when you land.
3° Now hit the ground hard and compress the tire while pushing on your legs in one firm extension, swing your free arm up leaning over the obstacle.
4° Bouncing back from the compression and extension phase, flap your arm down while pulling up the seat, this arm swing will drag you sideways.
5° Finish the arm swing in front of you while tucking the legs and bending at the waist, this will naturally adjust the uni under you, over the obstacle.
6° Just about landing on rubber, regain control with a few correction hops if necessary and stand up again to ride off to your next move.
Swinging your free arm is the real key, as this allows you to build up momentum sideways.
See the move in a video
Swing your free arm
In most unitrial moves, your free hand and torso are the drivers for precise positioning and landing. Make the most of it and let your free hand lead the move. By flapping your arm downwards, you support your own ascension (until you run out of swing, but by then you should have landed). Some riders grab the back or the front of the seat. But it is easier to pull the seat in front of you if you grab the back of it. Grab the seat by the front if you are confident you can sidehop while keeping the seat under you (seat-in). Also, you'll build some extra momentum sideways by tilting the uni sideways during the extension, leaning slightly over the obstacle with your shoulder.
A key to big side hops is to synchronize well the arm swing upwards with your extension, just after compressing the tire. Think of it like if you were jumping up to reach a ceiling with one hand. then you'll get a maximum lift (and height) by swinging your free arm down at the same time as you tuck the legs, bend the waist and pull the seat in front of you.
Going up forwards
To climb up forwards instead of sideways, lean forward during tire compression, and flap down your arm towards your knees when you tuck. This works best if you combine a frontal approach with a rolling hop. That is, rolling frontaly towards the obstacle, stalling briefly while pre-loading your extension, and jumping in one hop right when the uni and yourself haves tilted forwards. A variation of the sidehop is the pedal-grab where you use the front pedal to hook an edge and move up in two steps.