Preheat the oven to 200C/400F/Gas 6.
Place the red pepper halves and halved bulb of garlic onto a baking sheet. Drizzle with olive oil and season with salt and freshly ground black pepper.
Transfer to the oven and roast for 20 minutes, or until softened.
Meanwhile, bring a saucepan of water to the boil and blanch the runner beans until just tender. Drain the beans, then place into a large bowl.
Drizzle the beans with olive oil and balsamic vinegar and season well with salt and freshly ground black pepper.
To serve, place the roasted pepper and garlic halves on top of the beans and garnish with basil leaves.