Heat the oil in an 8-inch non-stick skillet over medium heat. Add the bacon and cook for 6 to 8 minutes or until browned and crisp. Remove the bacon and tip off most of the fat, leaving about 1 tablespoon in the pan. Once the bacon has cooled, crumble and set aside for the garnish. Raise the heat to medium-high and add the onions. Sauté for about 8 minutes, or until the onion is golden brown. Add the chiles and sun-dried tomatoes and cook for about 1 minute, or until the chile has softened. Pour in the beer and stir until the liquid has evaporated and the mixture is once again dry looking.
Reduce the heat to medium-low, sprinkle the cheese evenly over the vegetables and stir slowly and constantly until just melted—too long over the heat and the cheese will become tough, oily and stringy. Immediately scoop into a warm serving dish (a small fondue dish with a tea light below is ideal) and sprinkle on the crumbled bacon and chopped cilantro. Serve with warm tortillas or tortilla chips.