Thaw fish, if frozen. Rinse fish; pat dry. Brush both sides of fish with some of the oil. Sprinkle both sides of fish with the 1/4 teaspoon salt and 1/4 teaspoon freshly ground black pepper.

For vinaigrette: In a screw-top jar, combine vinegar, parsley, cilantro, the 2 tablespoons olive oil, lemon juice, shallot, garlic, the 1/2 teaspoon salt, paprika, red pepper, and cumin. Cover and shake well. Set aside.

For a charcoal grill, grill fish on the well-greased rack of an uncovered grill directly over medium coals for 6 to 9 minutes or until fish flakes easily when tested with a fork, gently turning once and brushing once with remaining oil halfway through grilling. (For a gas grill, preheat grill for 10 to 15 minutes on high heat. Reduce heat to medium. Place fish on greased rack over heat. Cover and grill as above.)

To serve, thoroughly shake vinaigrette. Divide couscous among 4 serving plates or shallow bowls. Use a wide spatula to transfer fish to plates. Drizzle the vinaigrette over fish. If you like, garnish with a lemon wedges, mesclun, and radish slivers. Serve immediately. Makes 4 servings.

Grill fish in foil packets. Fold four 24x18-inch pieces of heavy foil in half to make 18x12-inch rectangles. Place a fish fillet in center of each foil rectangle. Season with salt and pepper. Drizzle olive oil over fish. Bring up opposite edges of oil and seal with a double fold. Fold remaining edges together to completely enclose fish, leaving space for steam to build. Grill as above.