Place the mango, lime juice, tequila, and Cointreau in a blender and blend until smooth. Add the ice and blend to the desired consistency. If the mixture is too thick to blend, let it sit and melt for a few minutes.

If desired, use a lime wedge to moisten the rims of the glasses and then dip the rims in a small plate of salt.

Pour the mango mixture into the glasses and garnish with lime slices.