Fill a large pot with water, add a teaspoon of salt, and bring it to a rolling boil.
Cook the orzo pasta following the package instructions until it reaches al dente, stirring occasionally to prevent sticking.
Drain the pasta in a colander and rinse it under cold water until cool to stop the cooking process.
While the pasta cooks, combine olive oil, lemon juice, red wine vinegar, Dijon mustard, minced garlic, dried oregano, kosher salt, and black pepper in a bowl and whisk until fully blended.
In a spacious mixing bowl, toss the cooled orzo with the finely diced bell peppers, cucumber, red onion, corn, and fresh herbs.
Pour the lemon herb dressing over the salad and stir thoroughly to coat all ingredients evenly.
Adjust seasoning with extra salt and pepper according to taste if necessary.
Serve the salad immediately or chill it for a few hours or overnight to let the flavors meld and deepen.
Enjoy your fresh and colorful Rainbow Orzo Salad!