Combine first 5 ingredients in a large zip-top heavy-duty plastic bag. Add fillets; seal bag, and marinate in refrigerator 1 hour.
Prepare grill. Place fillets on grill rack coated with cooking spray, and grill 6 minutes on each side or until fish flakes easily when tested with a fork. Spoon White Corn Salsa over fillets, and garnish with carrots, beets, and thyme, if desired.