1. Cut pork crosswise into 1/2-inch slices; flatten each slice slightly with hand. Combine pork and Sriracha in a bowl, tossing to coat. Add sugar, garlic powder, and salt; toss well.
2. Heat a large nonstick skillet over medium-high heat. Coat pan with cooking spray. Add pork mixture to pan, and cook 3 minutes on each side or until done. Remove from heat; keep warm.
3. Combine spinach, cabbage, and bell pepper in a large bowl. Add sesame ginger dressing; toss well. Arrange 1 1/2 cups spinach mixture in each of 4 shallow bowls; top each serving with 3 ounces pork.