Salt the pasta water and cook the tri color rotini according to the package instructions to al dente. Once it is done, drain it immediately and rinse with cold water.
Add the bell pepper, cucumber, broccoli, and rotini to a large serving bowl.
In a small bowl, combine the mayo, sour cream, and ranch seasoning to make the creamy ranch dressing.
Stir the ranch dressing into the pasta and veggies until combined. Salt to taste, if necessary.
Refrigerate for 1-2 hours before serving. Pasta salad tastes best chilled but will dry out if you leave it too long. You can also stir in more ranch dressing before serving if needed.
Store leftovers covered in the fridge and enjoy within 3-4 days.
Notes
Most pasta salad will dry out some in the fridge, so if this happens I suggest stirring in a little bottled ranch before serving your leftovers.