Place the machine on a flat, level surface and make sure the condensation catch is in place. Install the auger and vessel according to the machine instructions. Add the drip tray and plug in the machine.
Pour the cold lemonade into the vessel, followed by the strawberry syrup. Close the cover and press the power button.
Select the SLUSH preset. Let the machine run for about 15–60 minutes, depending on the starting temperature of the ingredients.
When the machine beeps and the lights turn solid, place a cup on the drip tray.
Pull the dispensing handle forward to fill the cup, then release the handle to stop. Serve the Strawberry Lemonade Slush immediately.