In a small bowl whisk the glaze ingredients. Place the steaks in a shallow baking dish and cover with the glaze. Turn the steaks to distribute the glaze, and let marinate for 30 minutes at room temperature.
Prepare the grill for direct cooking over medium heat (350° to 450°F).
Brush the onion slices on both sides with oil and season with salt.
Brush the cooking grates clean. Grill the onions and the bell peppers over direct medium heat, with the lid closed, until the onions are tender and the bell peppers are blackened and blistered all over, turning occasionally. The onions will take 8 to 12 minutes, and the bell peppers will take 10 to 15 minutes. Place the bell peppers in a bowl and cover with plastic wrap to trap the steam. Let stand for about 10 minutes.
Remove the bell peppers from the bowl, discard the charred skin, stem, and seeds, and cut lengthwise into 1-inch strips. Place the peppers and onions on a serving platter and lightly drizzle with oil and the vinegar. Season with salt and pepper.
Grill the steaks over direct medium heat, with the lid closed, until cooked to your desired doneness, 8 to 10 minutes for medium rare (depending on the thickness of the steak), turning once or twice. During the last minute of grilling time, toast the bread over direct heat, turning once. Remove from the grill and let the steaks rest for 3 to 5 minutes. Cut the steaks into thin slices and serve warm with the peppers, onions, and toasted bread.