Prepare the grill for cooking over high heat (500°F).
Brush the cooking grates clean. Grill the bell peppers over high heat, with the lid closed, until the skins are blackened and blistered all over, 10 to 15 minutes, turning occasionally. Place the peppers in a small bowl and cover with plastic wrap to trap the steam. Set aside for at least 10 minutes, then remove the peppers from the bowl and peel away the charred skins. Cut off the tops and remove the seeds. Cut the peppers into ¼-inch strips and set aside. In a medium bowl whisk the remaining vinaigrette ingredients. Add the peppers and mix well. Set aside at room temperature until ready to serve. (May be made up to one day ahead; remove from the refrigerator 30 minutes before serving.)
Related Grill Skills
Lightly brush the fillets with oil and season evenly with salt and pepper. Grill over high heat, with the lid closed, until the flesh is opaque in the center, 5 to 7 minutes, carefully turning once. Serve warm with the vinaigrette spooned over the top.