In a bowl, combine the zucchini, shallot and salt. Let sit for 15 minutes. Drain.
In another bowl, dissolve the sugar in the vinegar. Add the remaining ingredients and the zucchini mixture. Mix well and season with pepper. Let marinate for 1 hour before serving. The zucchini and tomato concassé will keep for 2 days in an airtight container in the refrigerator. Delicious served with chicken or rice.