Mix together all the spices for the seasoning mixture (rub).
Then cut the flank steak in a butterfly cut and rub it with the rub. Then cut the mozzarella, paprika and mushrooms into thin slices and cover the opened flank steak with them. Now carefully roll up the topped flank steak against the grain and fix the end with a wooden skewer.
Now grill the side roll at around 200 to 220 degrees in direct heat for 3 to 4 minutes on each side. Then let it steep for 15 to 20 minutes in the indirect zone.
In the meantime, cut all the ingredients for the salsa into small cubes and mix with the mango chutney in a bowl. Season with salt and pepper and serve with the sliced flank roll.