In a 12 to 14-inch saute pan, heat 2 tablespoons olive oil over high heat until almost smoking.
Add the peppers and saute over high heat 4 minutes, until browned at the edges and softened. Add the sherry vinegar and salt and pepper, to taste, reduce the heat to medium, and continue to cook for 5 to 7 minutes, until peppers are tender. Adjust seasoning and set aside to cool.
Preheat the grill or broiler. Grill each slice of bread on both sides until crusty and browned, then top with peperonata and serve.