Prepare your meat and vegetables by cleaning, seeding, cubing and chopping. Thread a piece of green pepper onto the skewer. Follow it with a cube of beef, then one half of a preserved lemon, a couple of pieces of red onion, another piece of beef, a piece of red pepper and top it with a mushroom. Repeat the process with the rest of the skewers. Set all of the kabobs into a roasting pan in one layer and set aside.