Preheat the oven to 400 degrees F. Bring a pot of water to the boil. When boiling, add the asparagus and cook for one minute. Drain well, cool in ice-cold water, drain well again, and pat dry.
Place the asparagus in a single layer in a small casserole dish. Drizzle with the olive oil and balsamic vinegar; sprinkle with the red bell pepper, pine nuts, salt and pepper. Roast for 20 minutes, and then serve.