If I have a little more time to spend on the sauce, though, my favorite thing to add is roasted bell peppers. Previously I've used a recipe that has you halve plum tomatoes and roast them for an hour at 375 with a red bell pepper and an entire clove of garlic wrapped in foil. The garlic part I'm a big fan of, but I think I might actually prefer simply using a can of tomatoes. Some people might think you're sacrificing flavor, but it's so much easier -- not to mention skinless.
Here's my new favorite pasta recipe. It makes enough for about four generous helpings that require bread to slop up the extra:
Roasted Bell Pepper Sauce
3 red, orange or yellow bell peppers
14.5-ounce can tomatoes
3 T. extra-virgin olive oil, divided
2 cloves garlic, minced
1/2 t. kosher salt
Heat grill on high. Rub 1 T. olive oil on the cut side of the olive. Leave the skin on. Place onion cut side down on grill along with whole bell peppers. Check peppers every 5 minutes and turn to char the entire pepper. Turn the onion once or twice while peppers are cooking. When peppers are blackened and onion is soft, remove from grill. Place peppers in a bowl and cover with plastic wrap.
After vegetables are cool enough to handle, chop the onion, then remove the skin and seeds from the peppers and chop them. Place onion, peppers and tomatoes in a food processor and pulse until the sauce is well blended.
Heat 2 T. olive oil over medium-high in a skillet and cook garlic for about a minute. Add sauce and salt, and cook until heated through. Mix with your favorite pasta, and serve with fresh Parmesan.