Heat about 1/4-inch of oil in a large, heavy skillet or saute pan over medium heat.
In a large bowl, combine the masa, Essence, and sugar. Whisk in the milk, using as few strokes as possible. Add the bacon grease, queso blanco, roast pork, jalapeno, and garlic and stir to combine, being careful not to overwork the dough. Bring together into a ball.
Using your hands, form the dough into smaller balls and form into smooth patties 4-inches in diameter, about 1/2 to 3/4-inch thick. Refrigerate until ready to use.
Cook the arepas in batches until golden, about 6 minutes per side, turning and lowering the heat as necessary if they begin to brown too quickly, and pressing down with a spatula to flatten slightly as they cook. Remove and drain on paper towels, seasoning lightly with Essence. Repeat with the remaining batter, adding more oil as needed. Sprinkle each arepa with some of the remaining cheese and serve hot with the sour cream, if desired.