How can I make my tomato-herb pasta sauce a lighter color? I've been making a simple tomato sauce using tomato puree, basil, oregano, dried pasilla peppers, and garlic (as well as the left-over bits from cooking beef meatballs in the same pot). The flavor is good, but the sauce is visually very dark: a dark red that isn't very appetizing. I think this is because of the amount of basil I'm adding, but I'm not sure.

What techniques can I use or changes can I make to my recipe that will lighten the color closer to the red color of the tomato base, without changing the flavor too much?
Maybe too much basil, depending on how much you are using.  It really only takes a couple of leaves to add flavor, if you are using fresh.  I would not recommend dried.  You are probably also getting color from the dried pasilla pepper.  You could leave that out.  If you want a hit of pepper, add some to your final presentation. Cooking time will also effect the color of a tomato sauce.  Try cooking for a shorter time.  My basic tomato sauce cooks for 20 - 30 minutes.