1. Mix vinegar, soy sauce, brown sugar and 2 tbsp (30 mL) sesame oil in large bowl. Mix 3 tbsp (45 mL) of the vinegar mixture, Chinese five spice and garlic powder in resealable plastic bag; add shrimp. Refrigerate 15-20 minutes.
2. Add radishes, cucumber, shallots and lime juice to remaining vinegar mixture in bowl. Let stand 15 minutes.
3. Meanwhile, grill shrimp over medium-high heat about 2 minutes per side or just until shrimp turn pink and grill marks appear. Brush bok choy with remaining 2 tsp (10 mL) sesame oil. Grill, cut side down 2 to 3 minutes or until lightly charred.
4. Place cooked rice in bottom of 4 serving bowls. Top each bowl with bok choy, poke and shrimp. Sprinkle with sesame seeds.