Preheat oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer). Coat a baking tray with some oil. Wash the tomatoes and cut them in half horizontally. Reassemble and place on the baking tray.
Bake in a hot oven for about 15 minutes.
Carefully squeeze the mozzarella between kitchen paper and cut it into 16 slices. Wash the basil, shake dry and pluck the leaves from the stalks. For the vinaigrette, mix vinegar, honey, salt and pepper.
Fold down 3 tablespoons of oil.
Take the tomatoes out of the oven, carefully remove the top halves. Season lower halves with salt and pepper. Cover each with 2 slices of mozzarella and basil, except for a few leaves. Place the upper tomato halves back on top and drizzle with vinaigrette.
Continue baking at the same temperature for about 5 minutes. Remove from the oven and sprinkle with pesto. Sprinkle with the rest of the basil. Ciabatta tastes good with it.