For the salad, first make the oven tomatoes. These tomatoes are best if made a day before, or least given time to chill down in the refrigerator, so they become chewier and absorb the oil.
Preheat the oven to 180 °C (350 °F) Gas 4.
Put the halved tomatoes in a shallow ovenproof dish and drizzle the olive oil over the top. Tear the basil leaves over the tomatoes, the season with salt and pepper. Roast in the preheated oven for about 15 – 20 minutes, giving them a shimmy halfway through. Remove from the oven and let cool, then refrigerate.
When you are ready to serve, make the mustard dressing by simply combining the olive oil, vinegar, honey and mustard in a bowl, seasoning with salt and pepper, and mixing well.
Dress the salad leaves/greens with most of the dressing (reserving a little dressing for drizzling on top) and divide between 4 serving plates, then pop the torn mozzarella (or 8-9 mini mozzarella pearls/balls per serving), chilled oven tomatoes and bresaola slices on top, dividing them evenly between each plate. Drizzle the salads with the remaining dressing so that you get a taste of it even with the first mouthful, and serve immediately.