Start by preparing your glasses: rub the rim with a lime wedge and dip into a small dish of coarse salt, then set aside.
Measure out the freshly squeezed lime juice, tequila, triple sec, and optional simple syrup, then add them to your blender.
Add the ice to the blender, aiming for a mix of crushed and chunkier pieces for the perfect slush.
Secure the lid and blend on high until the mixture is smooth, icy, and frosty, about 30-60 seconds. You should see a thick, slushy texture with tiny ice crystals.
Taste the mixture and adjust with more lime juice or a touch of simple syrup if you prefer it more tart or sweeter. Give it a quick pulse to combine.
Pour the frozen margarita into your prepared glasses, making sure to keep the icy, slushy consistency intact.
If desired, garnish with a sprig of fresh mint for a herby aroma and a pop of color.
Serve immediately with a straw or spoon, enjoying the icy crunch and bright citrus flavor with every sip or bite.