Preheat the oven to Gas Mark 6, 200°C, fan180°C. Cut the peppers in half through the stalks and carefully remove the seeds. Put on a baking sheet.
Scatter the garlic and capers evenly among the peppers. Drizzle with the oil and 1 tablespoon cold water. Season well. Roast in the oven for 30-40 minutes until tender.
Remove from oven. Put on a serving dish. Add the rocket and drizzle
over the sherry vinegar and serve.
Roasting red peppers brings out their delicious sweetness. Make up to a day ahead and garnish with the rocket just before serving.