In a small bowl whisk together the garlic, dried oregano, Dijon mustard, red wine vinegar, salt, pepper, and a pinch of sugar. Still whisking, add the oil slowly to create an emulsion.
For the Salad
In a large bowl toss the lettuce, tomatoes, cucumbers, green bell peppers, onions, garbanzo beans and Kalamata olives with desired amount of vinaigrette. Add the Feta cheese and chopped parsley and toss gently. Adjust seasoning to taste.