In a large, covered, non-stick pot, bring water and chicken or vegetable bullion to a boil. Add orzo and reduce to a low boil and partially cover. Cook, stirring frequently for 7 minutes. Move orzo to a large bowl and set aside to cool.
Prepare the dressing by placing all of the ingredients in a mason jar, tighten the lid, then shake.
When orzo has cooled, add tomatoes, onion, basil, mint, cucumbers and 3/4 of the dressing. Toss. Chill for at least 3 hours, preferably overnight.
Add remaining dressing and toss right before serving.