Preheat the oven to 200C/400F/Gas 6.
Place the pepper half onto a baking sheet, drizzle with olive oil and season well with salt and freshly ground black pepper.
Transfer the pepper to the oven and roast for ten minutes, or until tender.
Mix the mustard and vinegar together in a large mixing bowl. Chop the broccoli into 2cm/1in pieces and add to the bowl.
Cut the warm pepper into slices and add to the bowl, along with the sliced tomato and chervil. Mix well.
To serve, place the salad onto a serving plate.