In a skillet over medium heat, melt 1 tablespoon of cooking oil and 1 tablespoon of unsalted butter. Add sliced medium yellow onions, cooking slowly as they soften for about 15–20 minutes until golden brown.

In a separate skillet, crack 4 large eggs, stir gently, place over medium-low heat, and add remaining butter. Cook for about 5–7 minutes, stirring slowly, seasoning with salt and chopped chives until just set but creamy.

In a small bowl, combine 2 tablespoons of mayonnaise with 1 tablespoon of sriracha. Mix until thoroughly blended to create a creamy sriracha sauce.

Butter the inside of a brioche bun, toast in a skillet over medium heat until golden, then spread sriracha mayo on both sides, layer the scrambled eggs, cheddar cheese, and caramelized onions.