Place the fresh lime juice, triple sec, tequila, simple syrup, and ice cubes into your blender.
Pulse the blender a few times to break up the ice, then gradually increase the speed to blend everything until smooth and icy. The mixture should have a thick, slushy texture with a vibrant green hue.
Stop blending once the mixture is well combined, thick, and scoopable. If it’s too thick, add a splash of lime juice and pulse briefly; if too runny, add more ice and blend again.
Pour the frozen margarita slushie into chilled glasses or bowls. Optionally, garnish with lime wedges or a sprinkle of salt on the rim.
Serve immediately with a spoon or straw, enjoying the icy, citrusy burst of flavor with a refreshing chill.