Heat olive oil in a pan over medium heat. Add onions and sautee for 10 minutes until softened.
Season with salt and sautee for a few more minutes. Then stir in brown sugar and allow to cook for another 10 minutes until browned and caramelised. Set aside.
Making the steak sandwich
While the caramelised onions are cooking, season steak with salt and black pepper.
In a small bowl, mix together garlic powder, paprika, dried rosemary, and olive oil. Rub the mixture all over the steaks.
Heat a grill pan over high heat. Sear the steaks on both sides until browned.
In the meantime, preheat oven to 180°C.
Slice open the sandwich rolls to create a pocket. Spread butter on the insides of each sandwich roll, then add in a slice of cheese, the steak, and stuff with caramelised onions.
Heat the stuffed sandwich rolls in the oven for 5-10 minutes until the cheese started to melt.
Garnish of chives and serve immediately.
Feel free to use nicer cuts of steaks, but for the theme of cheap & easy, I usually go for affordable topside beef or the likes of flank steak/flat iron steak
Ways to save time:
You can make the caramelised onions beforehand. Simply store the cooked onions in an airtight container and keep refrigerated for up to 4 days. Reheat in the microwave or add to the sandwich before heating the whole sandwich in the oven.
Prep the sandwiches beforehand by assembling everything together and skipping the oven part (i.e. the last step). Double-wrap the sandwiches with clingfilm and keep them refrigerated for up to 3 days. You can heat the sandwich in the oven or an air fryer!