Place the 2 tablespoons of lime juice in one shallow bowl or plate and the salt in another. Press the rim of a glass in the lime juice, then in the salt to coat. Repeat with the second glass.
In a blender, blend together the mango, 1⁄4 cup lime juice, tequila, and Grand Marnier until smooth, about 30 seconds.
Divide the frozen drink between the 2 glasses and serve garnished with lime wedges.