1. Remove any skin and dark areas from fish steak and cut into 30 cubes.
2. Puree all remaining ingredients except bell peppers and onion in a blender or food processor.
3. Pour puree over fish and toss to coat evenly. Marinate in refrigerator for at least 1 hour.
4. Seed peppers and remove cores and fiber. Cut into 30 squares. Cut onion into about 8 wedges top to bottom and separate the layers.
5. Thread one piece of fish, one piece of bell pepper and one piece of onion on a metal skewer and repeat four times. Then repeat with five more skewers for a total of six skewers each with five pieces of fish.
6. Broil or grill till fish is cooked to your liking. Actual time will vary.