6-7 medium limes
3 cups sugar (about)
3 tablespoons tequila, preferably silver
1 tablespoon triple sec or Cointreau liqueur
Zest the limes, measuring 6 tablespoons to 1/2 cup lightly packed lime peel (The strips of peel should be no wider than about 1/4 inch).
Using a sharp knife, peel off the white pith from the limes and discard it.
Chop lime fruit, eliminating the seeds; measure 1 1/3 cups of pulp.
Place the zest in a heavy nonreactive saucepan; cover with water.
Bring to a boil over high heat; boil 1 minute, and pour off water.
Add the chopped pulp and 3 cups water to the pan; let the mixture stand, lightly covered, for at least 4 hours or up to 24 hours.
Sterilize 3 half-pint canning jars.
Bring the mixture to a boil; boil until the fruit and zest are tender (about 10 minutes).
Measure the fruit and its liquid and add an equal amount of sugar.
Bring the mixture back to a full rolling boil; boil until it gels, which may be as little as 3 minutes more since it is already hot.
Spoon a teaspoon of the marmalade onto a chilled saucer; let the mixture sit for about 10 seconds, then tip the sauce of bit; if the liquid separates and runs like water across the plate, it is not done yet.
Test every minute or two, until the marmalade holds a soft shape.
Stir in the tequila and Triple Sec.
Pour the marmalade into the jars, leaving at least 1/4 inch headspace.
Cover, cool, and refrigerate, or process in a boiling-water bath for longer storage.
Store upside down for the first few hours to help distribute the fruit evenly.
It takes at least several hours for the marmalade to set up.
It keeps refrigerated for several weeks.