Cut the tomatoes into 4 wedges, then cut the wedges in half and add to a bowl. Lop off the tops of the green onions, then slice the white and mostly light green parts really thin. Add to the tomatoes.
Add the olive oil, balsamic vinegar, brown sugar, dash of salt and pepper to a jar. Screw on the lid and shake to combine. Pour the dressing over the tomatoes and toss.
Add the herbs and gently toss to combine. Cover and refrigerate for a couple of hours before serving.