Preheat a sous vide water bath to 135F (57C).
Scrub the lemons under hot water and dry them.
5 Meyer lemons
Peel the yellow zest in strips with a vegetable peeler, leaving the white pith behind.
Place the zest in a quart canning jar and add the grain alcohol, leaving ½ inch of headspace. Close the lid finger-tight.
2 cups 151-proof grain alcohol
Submerge the jar so the water reaches just below the lid. Cook 2 hours.
Meanwhile, warm the sugar and water over medium heat, stirring until dissolved and clear. Cool completely.
2 cups Sugar, 2 cups Water
Remove the jar and cool to room temperature, about 1 hour, before opening. Open it away from any open flame.
Strain through a fine-mesh strainer, then a coffee filter if you want it clearer.
Stir in the cooled syrup, bottle, and chill until ice cold.