How To: You Only Need 3 Ingredients for This Amazing Pasta Sauce

One of my favorite things is finding an easy way to make what is normally a complex dish. Case in point: pasta sauce. Usually its depth of flavor is the result of fresh herbs, shallots, tomatoes, seasonings, olive oil, and a touch of dairy being cooked and added in stages. Long simmering mellows out each component's inherent character and turns pasta sauce into something that is far greater than the sum of its parts.

But guess what? Turns out you can still whip up a damned good sauce with only three ingredients. Yep, that's right: three ingredients, not including salt. The magic trio? Tomatoes. Butter. Onions. And that's it.

The Holy Trinity: Tomatoes, Butter, & Onion

Created by Italian food guru Marcella Hazan, this recipe has been around for ages and is my go-to on those nights when I want something delicious to eat but don't have the wherewithal to slice-and-dice a lot of ingredients.

Why This Recipe Works So Well

First off, the recipe is simple, which means there's less opportunity to mess it up. Secondly, the butter is key. As Harold McGee pointed out, butter is complex enough to work as a sauce all by itself.

The combination of its fatty, flavorful deliciousness mellows out the acid in the tomatoes and allows the onions to caramelize over long, slow heat. The flavors of both these earthy, complex vegetables (although technically a tomato is a fruit since it has seeds) become fully rendered because they are cooked in such a rich base.

Adding full-fat dairy and a pat of butter to finish a pasta sauce is actually an old restaurant/culinary school trick. Butter not only enhances flavor, as discussed above, but acts as a thickener and evens out the texture. It also lends the sauce a nice sheen that photographs well, as a food stylist once told me.

It goes without saying that the better your ingredients, the better your recipe. You can use fresh tomatoes if they're in season, but to be honest with you, I feel this recipe is almost better with good quality canned San Marzano tomatoes. It's also a lot easier with the canned tomatoes. I recommend unsalted butter, too, since that way you can control the saltiness.

As for the onion, pick a medium-sized sweet yellow onion. As our Ultimate Onion Cheat Sheet points out, yellow onions caramelize quickly, work well with long cooking times, and show their inherent sweetness after cooking, while white onions tend to be more sharp and pungent.

Shallots are usually a great addition, but they are on the mild and sweet side. In my opinion, you want a heartier onion to really make this sauce stand out.

How to Make the Sauce

My version of this recipe goes as follows: Cut one whole small, sweet onion into small dice. Here's how to do it like a pro. Melt about 4 to 6 tablespoons of butter in a large, shallow saucepan. If I am feeling decadent, I use a whole stick of butter but keep the other proportions the same. Add the onions and sauté until they turn a light golden color.

Add a little salt to taste. Next, open up a two-pound can of good quality unflavored tomatoes (whole, crushed, or cubed is fine) and add it to the butter mixture with the juices.

Let the whole thing simmer over medium-high heat, uncovered, crushing the tomatoes and stirring along the way. Be sure to season with salt and taste along the way, too. Let the sauce cook until the liquid has been reduced and the sauce is velvety and thick. This is why I prefer the wide, shallow saucepan, which helps liquid evaporate more quickly.

This can take about 45 minutes to an hour, but usually during that time I'm cleaning up, prepping/boiling pasta, or checking my emails and occasionally popping back in to give the sauce a stir. It's pretty low maintenance.

Variations on a Saucey Theme

Afterward, you have a rich pasta sauce that simultaneously manages to taste creamy and bright thanks to the combination of tomatoes and butter, while the onions add an underlying rich earthiness. This sauce works great not only on noodles, but in a pizza or as a dipping sauce. Freshly grated Parm or Pecorino Romano takes it to a whole 'nother level.

You can check out Marcella Hazan's original recipe, which calls for tossing out the onion before serving the sauce (in her version, the onion isn't diced, just cut in half and added for flavor), and her son Giuliano's take, which has some good tips and variations.

Want more quick tips and food tricks? Learn how to make two-ingredient pasta dough and cut way, way back on pasta cooking time. And if you just had to go for the store-bought sauce, here's how you can make it taste more homemade.

What are your favorite three-ingredient recipes?