How to Make It
In a large bowl, mix the wine with the olive oil. Add the pork and turn to coat. Cover and refrigerate overnight.
Drain the pork and discard the marinade. Lightly season the pork with salt and season generously with pepper. Overlap 2 slices of soppressata on a work surface; put a length of pork in the center and roll it up in the soppressata. Repeat with the remaining soppressata and pork.
Strip 2 inches of leaves from the thick end of the rosemary branches. Using a sharp paring knife, whittle the ends to points. Thread 2 onion wedges onto each branch followed by 1 pork bundle; repeat twice.
Light a grill. Lightly brush the grate with vegetable oil. Grill the skewers over a medium-low fire, turning until the pork and onions are cooked through and the soppressata is crisp, about 12 minutes. Serve at once.
Make Ahead: The pork bundles can be assembled earlier in the day and refrigerated before grilling.
Wine Recommendation: The spicy soppressata suggests a soft, dry red with smoky overtones and some spice to match. Consider the 1999 Vigna Nirane Dolcetto d'Alba or the 1999 Giacomo Conterno Dolcetto d'Alba.