If you want clean cuts of bread and thin slivers of tomato for your sandwiches (and not a crumbly, splattery mess), you need a serrated knife. But not every bread knife is up to the task of slicing ...

Preheat the grill to high. Cut the tomatoes in half and place on a baking tray cut-sides up so they fit, trickle with olive oil and season generously with salt and freshly ground black pepper.