Cut the brisket into thin slices, just as thin as you can, it is better to put more slices than one thick one.
Also thinly slice the cucumber.
We send the bread to the grill, and at this time we mix mustard and mayonnaise, you will have to look for the proportions on your own to understand how you like it best, I make about 1 part of mustard and 4 mayonnaise.
Remove bread and add sauce.
We put a lettuce leaf down, then a few slices of meat, cheese and a fresh cucumber.
We spread sauces on the second slice of bread and cover our sandwich.