In a large bowl, mix the cornmeal, salt, and oil. Gradually add the warm water, stirring until the mixture is smooth and homogenous. Let the dough rest for 5 minutes.
Divide the dough into six portions. Shape each into a ball, then flatten into a disc about 4-5 inches wide and ½-inch thick.
Heat a large skillet over medium heat and brush with oil. Cook the arepas for about 6-7 minutes on each side until they are golden and crispy. Optionally, finish by baking in a 350°F (175°C) oven for 10-15 minutes for extra crispiness.
Combine the shredded chicken, onion, cilantro, and jalapeño in a bowl. In a separate bowl, mash the avocado with mayonnaise and lime juice until smooth. Mix the avocado blend into the chicken mixture until well combined. Season with salt and pepper.
Slice an opening on one side of each arepa to create a pocket. Generously fill each arepa with the Reina Pepiada mixture.
Serve the arepas immediately, or keep them covered to stay warm until ready to serve.
