01 -
Melt butter with neutral oil in a pan over medium-low heat. Add diced onions and salt. Stir every few minutes and cook gently until onions become golden and caramelized, about 30 minutes. If browning too quickly, reduce heat to avoid burning.
02 -
In a mixing bowl, combine mayonnaise, ketchup, vinegar, sweet relish, sugar, and optional chili flakes. Stir until fully blended and set aside.
03 -
Bake or fry frozen French fries according to package instructions until crisp and golden.
04 -
Arrange hot fries on a serving platter. Place American cheese slices or shredded cheddar evenly over the fries. Place under the broiler for 3 to 5 minutes until cheese is melted.
05 -
Spoon caramelized onions evenly over the melted cheese, drizzle prepared sauce generously on top, and serve immediately.