You have the juicy meatballs, and now you need the spaghetti sauce to simmer them in! Caramelized Onion Pasta Sauce to be exact. This sauce is not so “tomato-y” or acidic as many homemade sauces end up because of a few secret ingredients. The first secret ingredient is not so secret as it is right there in the title: caramelized onions. When you take the time to deeply caramelize onions they reach a sweetness and depth that really adds a lot of flavor to tomato sauce. This takes time… about 30 minutes of time. You want to slowly saute the onions in butter over low heat so they perfectly caramelize and don’t burn. Consider that sweet onion flavor from french onion soup, and then combine it with tomatoes and pasta. Nice, right?
Another secret ingredient is butter. I mean, butter makes everything better, doesn’t it? Yes it does. Just two tablespoons of butter adds a creaminess and mouthfeel that our tastebuds just want. Finally, the third secret ingredient. Add just one tablespoon… half an ounce… of really nice balsamic vinegar at the very end of cooking. It’ll turn your sauce a deeper shade of red. Add one of Italy’s shining stars, and I promise it gives this sauce that “something” that people won’t be able to figure out, but they’ll love it. “There’s just something different about this sauce, and it is really lovely”, they’ll say.
I’ve played around with this caramelized onion pasta sauce several times in recent weeks and even had a batch in the freezer waiting to be swirled around with some spaghetti and meatballs, until I cooked and devoured them! You should probably make a double batch so you have some leftovers to enjoy later, too.
- 4 tablespoons unsalted butter, divided
- 2 yellow onions, peeled and roughly chopped
- 2 garlic cloves, peeled and smashed
- 2 28-ounce cans diced tomatoes
- 8 ounces (1 cup) vegetable or chicken stock
- 1 tablespoon dried oregano
- 1 teaspoon smoked paprika
- 1 teaspoon kosher salt
- 1 tablespoon balsamic vinegar
- In a large saucepan over medium-low heat, melt 2 tablespoons of the butter. Add the onions and garlic, and saute until deep golden brown, stirring occasionally, about 30 minutes.
- Add the remaining 2 tablespoons butter, tomatoes, stock, oregano, paprika, and salt. Bring to a boil, reduce the heat to low, and simmer 10 minutes.
- Use an immersion blender, or carefully transfer the sauce to a blender, and blend until smooth.
- Continue to simmer the sauce until ready to serve. Just before serving, stir in the balsamic vinegar.