To get a definitive answer, we consulted the “King of Cocktails” himself. The following recipes come from Dale DeGroff, former bartender at New York's famous Rainbow Room, author of the book The Craft of The Cocktail and president and founder of The Museum of the American Cocktail.
The Original Margarita
3/4 oz freshly squeezed lime juice
1 1/4 oz Cointreau
1 1/2 oz silver (or blanco) Tequila
Assemble all the ingredients in a cocktail shaker filled with ice and shake well to a slow ten count. Strain into the serving glass of choice (tumbler or cocktail glass if served without ice). If salting the rim of the glass, use only Kosher salt, never iodized. Just salt half the glass.
The Original Margarita Batch
Yields one gallon or about 47 4.5-ounce margaritas
The batch cannot be assembled simply by multiplying the ingredients by the number of drinks you would like to make. Additional sweetness in the form of simple syrup, and a little less tequila and lime juice is needed to make the batch work for 47 portions.
Don't forget to take into account the shaking of the drink, which provides the final and critical ingredient of any cocktail: the one ounce of water added by shaking. That is why it is so critical to shake a drink well and for the proper time.
32 oz freshly squeezed lime juice
16 oz simple syrup*
36 oz Cointreau
44 oz 100 percent blue agave plata tequila
Assemble all the ingredients in a container just a bit larger than a gallon and adjust sweetness with lime juice and simple syrup. If it tastes good to you, it is probably good.
Remember individual servings still must be shaken with ice, even if the mixtures is already chilled.
Note: To use the batch above for margaritas, an additional 1 1/2 to 2 ounces of simple syrup must be added to the blender for each serving to carry the flavor forward through all the additional water.
* How to Make Your Own Simple Syrup
Fill a container that has a screw top half way up with granulated sugar (if your grocer has Superfine or Bar sugar use that). Fill the rest of the way with pure water. Screw on the top, turn upside down and shake well. Set aside and if sugar settles out, shake well again to dissolve. It is not necessary to cook and room temperature water will do fine.