Mezzi Rigatoni with Parsley Pesto and Roasted Peppers and Red Onions

There is a splendid marriage singular flavor of caramel (from two different roasted vegetables) and fresh herbs in this colorful salad. Make this very easy for yourself and prepare both the roasted peppers and onions in advance. In fact, the pesto is a make-ahead, too. For the best flavor and most vibrant colors, and there are a lot of lovely ones here, assemble it before serving.