Cut all the corn of the cob with your chefs knife. Make sure you do not cut to deep into the cob, you just want fresh corn and not the cob. Set aside the corn and make a corn stock with the cobs by placing them in a pot and cover with 2 quarts of water. Bring up to a boil and then turn heat down to a simmer. Cook for one hour. Strain the stock and set aside.
Sweat the onion in butter on low heat for five minutes. You do not want any color on the onions. Add the corn and cook for twenty minutes until the corn is tender. Add 3 cups of corn stock to the pot and reduce by 1/2. Season with salt and fold in epazote.
In a rocks glass place ½ tbs of mayo at the bottom of the glass. Add ¼ c of the corn mixture. Squeeze a dash of lime juice on top of the corn and top with a tbs. of queso fresco. Repeat the layering process one more time starting with the mayo and finishing with the queso fresco. Top off the esquites with a dash of chile pequin.