Black Skillet Beef With Greens and Red Potatoes

1 lb top round beef
1 Tbsp paprika
11/2 tsp oregano
1/2 tsp chili powder
1/4 tsp garlic powder
1/4 tsp black pepper
1/8 tsp red pepper
1/8 tsp dry mustard
8 red-skinned potatoes, halved
3 C onion, finely chopped
2 C beef broth
2 cloves large garlic, minced
2 large carrots, peeled, cut into very thin, 21/2-inch strips
2 bunch (1/2 lb) mustard greens, kale, or turnip greens, stems removed, coarsely torn as needed nonstick cooking spray