Prep the glasses: Run a lime wedge around the rim of your glass. Dip into a mix of coarse salt and Tajin for a sweet-heat edge. Set aside.
Load the blender: Add frozen mango, tequila, triple sec, lime juice, agave (if using), ice, and a small pinch of salt.
Blend until smooth: Start low, then blend on high for 20–30 seconds.
Add more ice for a thicker texture or a splash of water for a looser sip.
Taste and tweak: Need more brightness? Add a squeeze of lime. Want it sweeter?
Add a touch more agave. Prefer stronger? Add a 1/2 ounce more tequila.
Serve: Pour into the prepared glass, garnish with a lime wheel or mango slice, and enjoy immediately.