Working with one slice at a time, place the beef between two sheets of plastic wrap.
On a clean work surface, using the flat side of a meat pounder or a small, heavy frying pan, pound out each slice to a thickness of about 2 credit cards.
The goal is to get the meat extremely thin without tearing it.
The slices should be about 2 inches by 4 inches after they are pounded.
As you work, stack the slices in their plastic wrap to one side.
Put the pistachios in a food processor.
Carefully pulse to process the nuts just to the consistency of a coarse meal (about the size of the panko) scraping down the sides of the bowl as needed.
Be careful not to over process or the nuts will turn to butter.
Add the panko, garlic, lemon zest, coriander, and cayenne and pulse to blend.
Add the lemon juice and purée until smooth.
Preheat the broiler.
Spread a thin layer of pistachio purée over each piece of meat.
Carefully roll the meat up, taking care to keep the pistachio purée stuffed inside.
Slide the rolled and stuffed sirloin pieces onto skewers.
You should fill the equivalent of four 15-inch skewers.
Brush each skewer of meat with olive oil and lightly season with salt.
Broil for 5-7 minutes, flipping halfway through.
The spiedini are done when cooked to medium-rare inside.
You may have to remove the smaller pieces from the oven earlier, as they will cook faster.
Serve right away.