In a small bowl mix the brown sugar, garlic and beer. Place the steaks in a resealable plastic bag and add the marinade. Place it in the refrigerator for 2 to 4 hours.
Preheat the grill to medium heat.
Once the steak is marinated take it out of the refrigerator and set aside so the meat can rise to room temperature, about 5 to 10 minutes. Remove steaks from plastic bag and dry steaks off with paper towels. Brush with oil season with salt and freshly ground black pepper and place on grill. Cook for 5 minutes on each side for medium rare. Once cooked let it rest for 10 minutes. Place on serving plates.
In a medium skillet, add butter, onions and mushrooms. Saute until golden brown, about 5 minutes. Place into bowl and set aside. In the same skillet add 2 tablespoons of oil. Crack the eggs over the skillet and fry. Once ready place mushrooms, onions and eggs on top of the steaks and serve.