Finally shred the peel from the four limes. You should have about 2 tablespoons. Stir lime peel into water. Let stand for 30 to 60 minutes. Strain lime peel mixture through a sieve and discard peels. Meanwhile squeeze limes to make 1/2 cup juice and set aside

Stir sugar into strained lime peel mixture until dissolved. Stir in reserved lime juice, tequila, and orange liqueur

Rub six glasses with lime wedges and dip into coarse salt. Pour tequila mixture over ice