In a medium bowl, whisk together the olive oil, vinegar, sugar, garlic, fresh minced dill, oregano, garlic powder, salt, and pepper until thoroughly blended. Alternatively, you may measure the ingredients into a jar, tighten the lid, and shake until incorporated, or blend together in a blender or mini food processor.
In a large bowl, combine the tomatoes, cucumbers, olives, and feta. Whisk or shake the dressing and pour over the top. Toss together until all of the ingredients are evenly coated.
Cover the salad and refrigerate for at least 4 hours, removing from the refrigerator 30 minutes before serving. Stir well, garnish with dill, and serve with a slotted spoon to drain off any excess dressing.