The Tantrum is known as one of the easiest inverts to land next to the Heelside Back Roll. But it comes with a more complicated edge then the edge you would use for a normal wake jump or Back roll. A tantrum is a trip flip style invert that requires an edge change at the wake. In other words if you approach on your heels you actually flatten the board before the wake and then switch to your Toeside edge to pop the trick. At first this is a very abnormal thing to do unless you take a few steps to get used to the tripping motion and the Trip Flip Style Edge.
The first step is to practice the edge change and a little bit of the pop with no wake in the picture. By cutting away from the wake you can edge out toward the flats, stop edging or flatten the board and then cut back toward the wakes to get the tripping motion. After your aggressive edge out flatten the board and let go with your back hand. Coast flat for a little while and then turn quickly or punchy back toward the wakes on your toes and pop up a bit by standing stiff with a touch of Ollie of the tail of the board. Practice this until you feel a tripping back popping motion before moving to the next step.
The next step of this sequence is a basic backside reentry pop of off the wake. A backside reentry pop positions you squared up to the wake with only your front hand on the handle just like the take off of the tantrum while at the same time you can Ollie pop off of your Toeside edge to get acquainted with the edge change you will use during a tantrum attempt. For this step don't take an approach, sit at the bottom of the wake with bent legs, drift up toward the top, lean over your toes and then Ollie pop up and out toward the flats to land back at the bottom of the wake. Remember this step is get you familiar with the pop of the tantrum only, not the approach.
After practicing backside reentries and getting familiar with the pop it's good to practice the approach separately from a tantrum attempt so you can get used to flattening at the right time before the wake to get into the squared up position. Take a wide edge out to set up, bend your knees while you coast and then approach the wake at half the speed of a normal aggressive tantrum approach. A few feet in front of the trough of the wake flatten the board and release your back hand. After flattening and releasing your back hand stop quickly at the wake in the squared up position and then do a small reentry pop. Practice this a few times to get comfortable with the approach.
The next step is very similar to the last but instead of doing a reentry pop and landing on the outside of the wake you will do a reentry pop and land on the inside of the wake. This helps you square up, pop but also keeps you moving in the same direction across the wakes as a Tantrum attempt. Use the same speed approach as the last step, flatten off, release your back hand, square up your shoulders to the wake and then pop off the wake in a tall position to do a one wake jump but with a bit of the tripping motion so you fall back a little as you leave the top of the wake to mimic the pop you need for the tantrum.
Remember, a tantrum is a one handed trick so you should have your back hand off the handle before you get to the wake or you won't be able to square up, flatten or pop straight up like you need to in order to flip easily. Practice this sequence before every session of wake to wake tantrum attempts and you will quickly engrave the tripping motion and the trip flip edge you will need for this easy to achieve first invert.