Melt the butter together with the oil on a cooking pot over medium-high heat. Add the chopped chiles and let them cook for about 20 to 30 seconds, moving them around.
Incorporate the corn, chopped fresh epazote leaves or dried epazote leaf, water and salt. Stir it all up and bring to a simmer. Cover with a lid, bring heat to medium-low and cook for 12 to 14 minutes, until the corn is cooked but still tender. Turn off the heat. You may leave the corn in the pot for a couple hours.
Serve corn in cups or small bowls. Let your guests add to their liking the fresh limejuice, mayonnaise or Mexican cream, crumbled cheese, powdered chile piquín and salt.
You may also cook the whole corn in salted water with the epazote leaves. Once it is cooked and ready, garnish with the same ingredients.