Place the tomatoes, cut-side up, in a small roasting tin. Drizzle over the olive oil and season with a little sea salt and pepper. Roast in a preheated oven, 200°C (400°F), Gas Mark 6, for 20 minutes until wilted and softened. Remove from the oven and leave to cool.
Make the dressing. Place the rocket and basil leaves, 2 tablespoons of the extra virgin olive oil and the vinegar in a small bowl. Blend with a stick blender to a purée, or transfer to a mini food processor to blend. Stir in the remaining oil and season to taste with salt and pepper.
Arrange the roasted tomatoes on a platter, then tear the mozzarella balls in half and arrange among the tomatoes. Drizzle over the dressing and scatter over the pine nuts. Serve immediately with ciabatta.