For the sunshine dressing: Add the mayonnaise, sour cream, mustard, lemon zest, lemon juice, garlic, salt and pepper to a medium bowl and whisk until combined.
For the salad: Cook the pasta in salted water according to package instructions. Drain and rinse the pasta under cold water. Allow the pasta to dry slightly before assembling; this will help the dressing really adhere to the pasta.
Pour the dressing over the pasta in a large bowl and toss to coat. Add the yellow and grape tomatoes, corn, bell peppers and banana peppers and toss gently until evenly mixed. Arrange the salad onto a serving platter and garnish with the lemon slices.