01 -
Heat butter and olive oil in a skillet over medium-low heat. Add the sliced onions, sugar, and salt. Cook, stirring occasionally, for 25-30 minutes, until golden brown. Remove from heat and set aside.
02 -
Pat steak dry with paper towels. Rub with olive oil, salt, black pepper, and garlic powder. Heat a grill pan or skillet over medium-high heat. Sear the steak for 3-4 minutes per side for medium-rare (adjust for doneness). Let the steak rest for 5 minutes, then slice thinly against the grain.
03 -
Spread butter on one side of each bread slice. In the same skillet, toast the buttered side of the bread over medium heat until golden and crisp.
04 -
Place a slice of cheese on the toasted side of one bread slice. Add sliced steak, a generous scoop of caramelized onions, and another slice of cheese. Top with the second bread slice, toasted side in. Return the sandwich to the skillet and cook over medium heat for 2-3 minutes per side until the cheese is melted and the bread is crispy.
05 -
Slice the sandwich in half and serve hot for the perfect balance of flavors!