Sofia Head grew up watching her grandfather lead the carne asadas, her family cookouts, in Monterrey, Mexico. He manned a charcoal grill for hours, cooking carne asada for dozens of relatives. One of her favorite dishes was his queso fundido: melted Chihuahua cheese in a cast-iron skillet that he left on his grill until the queso’s edges became crisp and the center was bubbly.