Cook the veggies in a bit of olive oil until their juices reduce and then add the cooked beef, the sauces, and season them with salt and pepper as you like
Add the cheese and it will mix with the juices and form a nice sauce
Toast your bread and add the beef mix on top. We ate them open faced so we could eat more of the filling
Notes
1- I use Mozarella and Emmental mix; you can use any melty cheese you like2- Add Salt and Pepper to taste3- This made 5-6 sandwiches so you could definitely half the recipe if needed. Enjoy!