Why anyone would use jarred tomato sauce is a total mystery to me. Loaded with salt, sugar (in the form of high-fructose corn syrup), and chemicals, overcooked, and then pasteurized, even the best of the jarred sauces tastes like...well, crap. I've heard all the excuses, "it takes too long to make my own sauce," "I'm not Italian, what do I know about making sauce?" "I don't have time to cook sauce after working all day." Poppycock. In the time it takes to boil water and cook the pasta you're going to serve it with, anyone (well, almost anyone, but that's another story) can make homemade tomato sauce from either fresh tomatoes or from high-quality packaged tomatoes.
When I first met my wife (happy 25th anniversary, honey), she thought she couldn't make tomato sauce. She was intimidated, she said, because of my Italian background. In one lesson, I taught her to make as good a sauce as my grandmother. In two lessons, she had left Nona in the dust. And Nona claimed to have taught Chef Boiardi how to cook. Which would explain a lot. (For the record, I think that Nona was speaking metaphorically, since Boiardi lived in Cleveland, and Nona had never been west of the Hudson River.)
The secret to a great quick sauce is in not expecting a "Sunday" sauce. Sunday sauce was traditionally started early Sunday morning (duh), right after Mass. The women would come home from church and start to cook. Meatballs, braciole (both of which were made from scratch on Saturday), sausage, and pig's knuckles were all browned and added to fresh tomatoes that had been canned the previous summer. This would simmer for hours, until the meat was tender and the sauce was thick and rich. Can you get that taste in 30 minutes? Absolutely not. You can't get it out of a jar either, though, so why bother trying? But what you can do is to make a very, very good marinara style sauce in 30 minutes.
To begin with, start boiling water for the pasta. There are rules about which shapes go with which sauces, but for now, let's just concentrate on long pasta (spaghetti, linguini, cappellini, perciatelli, etc.). While the water's heating, thickly slice some cloves of garlic and roughly chop a small onion. Heat a cast iron skillet over medium high heat and add about a tablespoon of olive oil. When it's just starting to shimmer, add the onions. Let cook for about two or three minutes and then add the garlic. Lower the heat to medium and cook, stirring, until the garlic begins to color. As soon as it does, add a pint of cherry tomatoes (for two people). You could slice them in half, if you'd like, but it's not necessary. Turn up the heat to medium high again, and cook, stirring or shaking the skillet. The tomatoes will begin to break down, releasing their liquid. The water should be coming to a boil about now, so add your pasta to it. Allow most of the liquid that the tomatoes have lost to evaporate, and let the tomatoes begin to caramelize (the natural sugars will begin to turn brown. Only foods with sugars caramelize. Meat does not!). Add some hot red pepper flakes, and turn off heat.
Cook the pasta until al dente, which means "to the tooth" (it should yield easily to the teeth, but have a bit of resistance or even crunch in the center), bearing in mind that pericatelli will take longer to cook than cappellini, drain the pasta and put it into the skillet with the tomatoes, toss to mix, add some torn basil and some freshly grated parmigiano reggiano or asiago cheese, and serve.
For pasta alla putanesca, add four anchovy fillets with the onion, up the red pepper at the end, and instead of basil, add a teaspoon of chopped capers, about 15 chopped kalamata olives (for god's sake, never use canned olives), and a handful of chopped parsley. With this sauce, rather than cheese, add the juice of half a lemon just before serving. The anchovies and olives add depth and smokiness, and the lemon adds a brightness that lightens the dish and enhances the flavor of the capers.
Want to get fancy? Toss in some sliced crimini mushrooms before the tomatoes. Let them brown, and give up all of their liquid. Grate a pinch of fresh nutmeg on the mushrooms, swap some fresh thyme for the basil, and use freshly grated black pepper rather than hot red pepper flakes.
Want to add meat? Before adding the tomatoes, add some sliced (or, better, crumbled) Italian sweet or hot sausage, some ground pork, some sliced chicken, or some bacon. Allow to brown, and then add tomatoes.
Want a thicker sauce? Start with crushed tomatoes. Stay away from cans; they're loaded with sodium (one brand has 300 mg of sodium per serving, and 13 servings per can!). Rather, buy Pomi chopped tomatoes. They come in a box, are imported from Italy, and taste almost as good as fresh. Let them cook at a slightly higher temperature, since they have more moisture.
Try different kinds of tomatoes! Grape tomatoes are sweeter. Roma (or plum) tomatoes are not as moist. Round "salad" tomatoes are slightly less acidic (and also less flavorful).
All of these sauces are infinitely variable, depending on your taste. Experiment! What have you got to lose? In the time it takes to cook pasta (which you'd have to do anyway), you can serve a delicious homemade tomato sauce that will blow any jar out of the water. Buon appetito!