Peel and thinly slice the onion into semi-circles. Then place the semi-circles into a bowl of ice water and let soak for 30 minutes. After 30 minutes strain and pat dry with paper towels.
Place a large pot filled with water on the stove top and salt to taste. Once boiling, add the pasta, stir, and cook for the directed amount of time on the package. Usually 10-12 minutes. Once cooked, strain and rinse well with cold water and allow to drain in the colander for 10 minutes.
Transfer the pasta to a large bowl and add the soaked onions, cucumber, kalamata olives, cherry tomatoes, red bell pepper, and half of the feta cheese. Set aside.
To make the dressing: In a medium bowl combine the extra virgin olive oil, red wine vinegar, minced garlic, granulated sugar, dijon mustard, dried oregano, sea salt, and ground black pepper. Whisk vigorously until well combined.
Pour ¾ of the dressing over the pasta salad and toss until fully coated. Taste and add the remaining dressing if you like.
Sprinkle the remaining feta cheese over the pasta salad and serve.