1. In a small saucepan, combine the vinegar, syrup, and soy sauce. Simmer over low heat until mixture is slightly syrupy and reduced by one-third, about 10 to 14 minutes. Remove from heat and let cool to room temperature.
2. Place swordfish steaks in a resealable plastic bag. Pour the cooled balsamic-maple mixture into the bag, turn to coat fish, and refrigerate for at least 30 minutes, up to 2 hours.
3. While fish marinates, slice chard into 1-inch-wide ribbons, discarding anythicker or tough stems. Thoroughly wash the chard in cold water, drain in a colander, and set aside.
4. Preheat oven to 425 degrees F. Line a rimmed baking sheet with foil and spray with vegetable cooking spray.
5. Remove swordfish from marinade, reserving marinade in a small saucepan.Place steaks on the prepared baking sheet and sprinkle generously on both sides with pepper.
6. Bake the swordfish for 12 to 15 minutes, until just cooked through (fish should flake easily with a fork).
7. While fish cooks, heat saucepan with marinade over high heat and bring to a boil. Then lower heat and simmer for 5 to 10 minutes to reduce by about one-third.
8. While marinade simmers, heat oil in a large skillet over medium heat. Add the chard and saute, stirring just until wilted, about 7 minutes. Transfer the cooked chard to a serving dish or platter. Top with the cooked swordfish steaks. Drizzle the simmered reserved marinade over the fish and cooked chard. Serve immediately.
Source: Fresh Magazine March, April 2010