Preparation Char chiles over gas flame or in broiler until blackened all over. Place chiles in bowl; cover tightly with plastic wrap and let steam 15 minutes. Peel, leaving stem intact (do not tear flesh of chiles). Using small sharp knife, cut 1 long slit down side of each chile; carefully remove seeds. Toast cumin seeds in small skillet over medium-high heat until slightly darkened and aromatic, 1 to 2 minutes. Set chiles and cumin aside. Line rimless baking sheet with foil. Cook potatoes in large saucepan of boiling salted water until just tender, about 8 minutes. Drain. Transfer potatoes to medium bowl; cool. Add cheese, chopped oregano, and toasted cumin; stir to distribute evenly. Season to taste with salt and pepper. Carefully fill chiles with potato mixture, about 1/3 to 1/2 cup filling for each. Working with 1 chile at a time, hold in palm and squeeze gently to compress lightly. Place stuffed chiles on prepared sheet. Combine broth, juice, 2 teaspoons chile powder, and next 4 ingredients in heavy medium saucepan. Simmer over medium heat until slightly thickened and reduced to 2/3 cup, 8 to 9 minutes. DO AHEAD: Chiles and sauce can be made 1 day ahead. Cover and chill separately. Let chiles return to room temperature before continuing. Mix 3 teaspoons chile powder and 1 tablespoon coarse salt in small bowl. Sprinkle mixture over pork chops; let stand at room temperature up to 2 hours. Prepare barbecue (medium heat). Brush pork with oil. Place pork chops on 1 side of grill. Transfer chiles on foil to opposite side of grill. Grill pork chops until just cooked through, about 4 minutes per side; transfer to plate and let rest 10 minutes. Grill chiles until cheese melts, about 15 minutes. Rewarm sauce. Place 1 pork chop and 1 chile on each plate. Drizzle sauce over, sprinkle with oregano leaves, and serve. Often called pasillas; available at some supermarkets and at specialty foods stores, farmers' markets, and Latin markets. ** Available in the spice section of many supermarkets and at Latin markets. *** Available in tubes at some supermarkets and at Italian markets.