Step 1Combine the wine, olive oil, bay leaves, garlic and salt and pepper to taste in a bowl and let the pork cubes steep in the liquid, covered and refrigerated, for 4 hours.
Step 2Heat the broiler or grill to medium-high heat. Thread the pork along 4 flat metal skewers, patting dry slightly with paper towels. Grill the pork about 4 or 5 inches from the heat source for about 4 to 5 minutes per side (for a total of 16 to 20 minutes). Remove.
Step 1Strain the yogurt through a fine mesh strainer set over a bowl for 2 hours. It should be thick like sour cream.
Step 2Place the pork skewers on a platter. Dust generously with cayenne and top with the raw onions. Serve the yogurt on the side.