In small bowl, mix all dressing ingredients except oil.
Slowly add oil, beating with whisk until well blended.
Pour dressing over salad; toss to coat.
Notes / Tips / Wine Advice:
Instead of tossing the salad together in a bowl, try an arranged presentation. Slice the tomatoes and arrange colors alternately with onion on a decorative platter. Drizzle the dressing over the top, and sprinkle with the fresh herbs.