1. Preheat grill to medium-high. In a small bowl, mix together pepper, cumin, paprika, and oregano. Rinse flounder under cold water and pat dry with a paper towel. Rub one side of fish with oil, and put oil-side down on foil. Season both sides with combined spices.
2. Cut eight 20-inch-long pieces of foil. Layer two sheets for each packet (double layering will help protect the contents from burning). Arrange each fillet on one half of each double layer. Top fish with chives, 1 or 2 lemon slices, capers, snap peas, carrots, tomatoes, and fennel. Fold the foil over the ingredients and tightly seal the packets by crimping and folding edges together.
3. Grill for 10 to 12 minutes, rotating the packets 180 degrees about halfway through to ensure even cooking. (Don't flip the packets.) Let packets rest unopened for 5 minutes before serving. To serve, instruct diners to open the sealed side of the packet away from them, as the escaping steam can be hot. For a casual meal, eat directly from the foil, or place on a plate and serve with rice, if desired.
Source: fresh magazine May, June 2010