1. Heat a grill pan over medium-high heat. Coat pan with cooking spray. Combine chili powder, sugar, cumin, cocoa, and 3/8 teaspoon salt; rub spice mixture evenly over steak. Add steak to pan; cook 5 minutes on each side or until desired degree of doneness. Let stand 10 minutes; cut across the grain into thin slices. Cut bell peppers into quarters; discard seeds and membranes. Add bell peppers to pan; cook for 4 minutes on each side. Cut into thin slices.
2. Combine remaining 1/8 teaspoon salt, vinegar, oil, and mustard in a medium bowl, stirring with a whisk. Add jicama, radicchio, and cilantro to bowl; toss to coat.
3. Heat tortillas in grill pan coated with cooking spray 30 seconds or until lightly charred. Divide beef, bell peppers, and jicama mixture evenly among tortillas; serve with lime wedges.