Bring a large pot of salted water to a boil over high heat. Add the rotini whole wheat pasta and tri-color pasta, cooking according to package directions until al dente, usually about 8-10 minutes. Once cooked, drain the pasta in a colander and rinse it under cool water.

In a mason jar, combine olive oil, vinegar, water, dried basil, dried oregano, chopped fresh parsley, and a pinch of salt, pepper, and red pepper flakes. Secure the lid and shake vigorously for about 30 seconds.

In a large mixing bowl, combine the cooled pasta, diced red onions, chopped black olives, diced green bell peppers, and chopped roasted red peppers alongside halved grape tomatoes.

Pour the homemade Italian dressing over the pasta and vegetable mixture. Using a large serving spoon, gently toss the ingredients together until they are fully coated with the dressing.

Cover the bowl with plastic wrap or transfer the Vegan Pasta Salad to an airtight container. Refrigerate for at least 2 hours, preferably overnight.