Start by bringing a large pot of salted water to a rolling boil. Add the rotini pasta and cook according to the package instructions, usually around 8-10 minutes, until al dente. Once cooked, drain the pasta in a colander and rinse it under cold water to stop the cooking process. Drain well and set aside to cool completely.

In a small mixing bowl, combine the olive oil, fresh lemon juice, balsamic vinegar, and water. Add minced garlic, salt, and pepper to taste, then whisk vigorously until the dressing is well blended and emulsified. Stir in the fresh oregano, releasing its aromatic flavors, and set the vinaigrette aside to let the flavors meld.

In a large mixing bowl, add the cooled rotini pasta, then gently fold in the chopped tomatoes, sweet red pepper, cucumber, zucchini, red onion, and Greek olives if using.

Pour the prepared vinaigrette over the pasta and vegetables in the mixing bowl. Sprinkle the crumbled feta cheese on top, then gently toss everything together.

Cover the bowl with plastic wrap or a lid and place the salad in the refrigerator for at least 30 minutes.

Once chilled, give the salad a final toss to redistribute the dressing. Serve the rotini pasta salad on a platter or in individual bowls.