1 Rinse tomatoes and halve horizontally, then trim stem so top half stands upright.
2 Scoop out seeds and flesh from tomatoes with a teaspoon. Pass through a sieve into a bowl, pressing on solids with the spoon to extract as much liquid as possible.
3 Rinse zucchini, wipe dry and cut into about 5 mm (approximately 1/4-inch) cubes.
4 Stir the zucchini into the tomato pulp and season with vinegar, salt and pepper.
5 Toast the sesame seeds in a small dry pan until golden brown, tossing frequently, then stir into the zucchini mixture while still warm.
6 Rinse the mint, shake dry and pluck leaves. Reserve some leaves for garnish and finely chop the rest, then fold into the zucchini mixture.
7 Season zucchini mixture with salt and pepper, then spoon into the tomato halves. Garnish with reserved mint leaves and serve.