While fries are baking, heat oil and brown sugar in frying pan over medium heat.
Add chopped yellow onion and cook onions until caramelized.
Remove fries from oven and sprinkle with cheese. Return to oven and broil on high for three minutes until cheese has melted and fries begin to golden around edges.
In a separate bowl, mix together remaining ingredients for the sauce.
To serve, top cheese fries with caramelized onions and sauce.