Preheat oven (electric cooker: 225 °C/circulating air: 200 °C/gas: see manufacturer). Cut baguette into thin slices, halve slices. Place on a tray lined with baking paper, drizzle with 5 tbsp. oil and roast in the oven for approx. 10 minutes.
Meanwhile wash the tomatoes and cut them into smaller pieces. Peel and finely chop the onion. Wash basil and shake dry, remove leaves. Pluck the mozzarella. Mix vinegar with salt, pepper and sugar. Fold in 4 tablespoons of oil. Mix everything, add toasted bread and mix well.