Step 1: Prepare the pork and marinade: Place the pork in a nonreactive baking pan. Place the chile powder, vinegar, orange juice, garlic, salt, black pepper, oregano, cumin, and cinnamon in a blender and blend until smooth. Pour the marinade over the pork, turning the pieces to coat well. Let the pork marinate, covered, in the refrigerator for 1 to 4 hours.

Step 2: Grill the vegetables: Set up the grill for direct grilling and preheat it to high.

Step 3: When ready to grill, brush and oil the grill grate. Place the poblano peppers and bell peppers on the grate and grill until darkly browned on all sides, turning with tongs, about 15 minutes. Transfer the grilled peppers to a cutting board and let them cool. Meanwhile, grill the onion wedges and scallions until browned, 2 to 4 minutes per side, turning with tongs. When the peppers are cool, stem and seed them. Cut the peppers and onions into thin (1/2-inch) strips. Cut the scallions into 2-inch pieces. The vegetables can be grilled up to 30 minutes ahead. If grilling ahead on a charcoal grill, you may need to add fresh coals.

Step 4: Just before serving, heat the skillet in a 400°F oven for 10 minutes. (Or preheat the skillet on the grill.) Warm the tortillas (10 to 15 seconds per side), and place in the clothlined basket. Place the salsa, sour cream, and cilantro in separate small bowls with serving spoons.

Step 5: Just before serving, drain the pork slices well. Arrange on the hot grate and grill them until browned and cooked through, 2 minutes per side. Transfer the grilled pork to a cutting board and cut it into thin strips. You can serve the fajita ingredients hot off the grill. Or, for the sizzling platter effect, arrange the slivered pork and the vegetables in the preheated skillet and place the skillet on a trivet. Use tongs to load up the tortillas with sliced pork and grilled veggies. Top the fajitas with salsa, sour cream, and cilantro, and serve with lime wedges for squeezing.