2 people
15 mins
45 mins
More effort
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Step 1
In a heavy-based saucepan, slowly cook the onions in the butter and oil over a medium-low heat for around 25-30 mins or until soft, golden and reduced by more than half. Season with salt and set aside.
Step 2
Heat the gravy in a saucepan over a medium heat, then add the roast beef slices for around 3 mins until warmed through. Remove from the heat and spread the slices of bread with mustard, then layer the caramelised onions, cheeses and roast beef -reserving the gravy - between two slices for each sandwich. Press each down to seal.
Step 3
Lightly butter the outside of the sandwiches, then heat the sunflower oil in a frying pan. Fry the sandwiches for around 5 mins, pressing down with a pan lid or spatula and turning halfway through. Once the bread is golden and the cheese has melted, transfer to two plates.
Step 4
Cut the sandwiches in half and serve with the reserved the gravy on the side for dipping.
Make your toastie a cut above the rest with Lidl's 2.2kg Deluxe Aberdeen Angus beef joint. Cooking it couldn't be easier. Simply sear the joint on all sides in a hot pan for around 10 mins, then remove from the heat. Next, mix 1½ tbsp English mustard, 2 tbsp olive oil, a generous helping of black pepper and a pinch of salt, then brush the mixture all over the joint.
Heat the oven to 180C/160C fan/gas 4. Roughly chop 2 carrots, 2 onions and 2 celery sticks into large pieces, then spread on the base of a roasting tray. Place the prepared beef on top and roast for 1 hr 30 mins. Remove from the oven and leave to rest for 20-30 mins before slicing and serving. Save the resulting juices in the tin for your gravy, and cover and chill any leftover beef, so it can be used in this toastie!