Last Updated on April 12, 2024

Use your home grown tomatoes from the garden to make this simple Caramelized Onion and Garlic Roasted Tomato Sauce! This fresh, garden-to-table pasta sauce is so flavorful by simmering the sweet and salty caramelized onions and garlic with the tomatoes, and classically herby with the addition of fresh basil and oregano. It’s perfect for pasta night tossed with your favorite gluten-free noodles!

For growing up in an Italian home, I realized that I don’t have very many Italian recipes on the blog 🤔 That needs to change. In fact, I’ve been pondering the idea of creating a whole cookbook dedicated to Italian cuisine… maybe that’s my next big project. But in the meantime, let’s dive into this Caramelized Onion and Garlic Roasted Tomato Sauce 🍅🧅🧄🥫.

Last year I made Garden Fresh Restaurant Style Canned Salsa with the abundance of homegrown early girl tomatoes that I harvested from my garden. This year, I wanted to make a homemade pasta sauce recipe.

With store bought tomato sauces becoming more processed and loaded with sugar, making your own sauce at home is the way to go, and it’s really quite simple.

The Simple Sauce Ingredients

Tomatoes. I was fortunate enough to have an amazing early girl tomato harvest this year ❤️. Using fresh, homegrown tomatoes makes THE BEST tomato sauce. But no worries, you may also buy them. You’ll need enough tomatoes to fill a 12×17 baking sheet- for me, that was 30 medium-large tomatoes.

Sweet yellow onions. You’ll need two large sweet yellow onions to make the caramelized onions.

Garlic. one medium head of garlic, approximately 12 garlic cloves are needed for this recipe. While I’m a big fan, I would not buy pre-minced for this sauce recipe.

Basil. I would recommend using fresh basil if possible, not dried. You’ll need 20 ounces (57 grams)- approximately 2 cups of loosely packed basil leaves. Using fresh basil just gives this sauce that extra fresh taste.

Oregano. same as the basil, you’ll need fresh oregano. You’ll need 0.75 ounces (21 grams) or 1/2 cup packed oregano leaves.

Olive oil. 1/4 cup of olive oil is used to caramelize the onions, not to put in the sauce.

Salt & pepper. You’ll need 1 tablespoon of salt to make the caramelized onions, and then more to taste (along with the pepper). I like to use Himalayan pink salt and I find the flavor to be better, but you can use regular ol’ table salt if desired.

The Caramelized Onions 🧅

I decided to make my own sauce with caramelized onions after I tried Rao’s Caramelized Onion Sauce and fell in love with it! 😍 I’m a big fan of caramelized onions, I could eat them straight from the pan! So adding them to the sauce being a whole different salty sweet flavor that compliments the acidity of the roasted tomatoes.

For ideas on other ways to use caramelized onions in recipes, be sure to check out my Quick & Easy Garlic Caramelized Onions blog post!

How To Make This Tomato Sauce

First, you’ll wash and roast the tomatoes in the oven for 30-35 minutes, until the tomato skins are wrinkly and start to brown. Then allow the tomatoes to cool slightly and peel the skins right off! Be careful, the tomatoes will release a lot of water during the roasting process and you may need to VERY CAREFULLY pour some of that water down the sink and keep roasting. Remove the tomatoes from the oven and allow them to cook slightly while you get the caramelized onions going.

To make the caramelized onions peel and slice the yellow onions and add them to a large skillet with 1/4 cup of olive oil and 1 tablespoon of salt.

Peel the garlic and add the garlic cloves to the skillet with the onions. Cook the onions and garlic over medium heat, tossing frequently until they caramelize, are very soft, and turn a golden brown color. This should take 30-35 minutes. If the bottom of the pan starts to burn, turn the heat down add a little water to the pan.

While the onions are cooking, peel the skins off the tomatoes (carefully if they are still hot!) add the whole, peeled tomatoes to a large stockpot and set aside.

Add everything to the pot with the tomatoes- the basil, oregano, and caramelized onions.

Bring the sauce to a boil and then cover and simmer for 2 hours, or longer if desired.

Using an immersion blender, blend the sauce to desired consistency. It will thicken up more as it cools. If you don’t have an immersion blender you can pulse it in your blender, but don’t blend it too much- we’re not making tomato soup here! 😜

Sauce Recipe Tips & Variations

The Tomatoes. Let’s talk tomatoes. My tomatoes were very red and sweet this year, which allows this sauce to have an amazing flavor. Using high-quality tomatoes is the best for the best tasting sauce. You may buy tomatoes for this recipe if you didn’t grow your own tomatoes this summer, but try to buy organic if you can. Tomato quality has really been decreasing over the years, and I find that organic is the best you’ll get to fresh, homegrown tomatoes.

Sugar. There is no added sugar in this tomato sauce recipe. That’s kinda the point… the caramelized onions add so much sweet flavor, BUT if your tomatoes aren’t super sweet or of the highest quality (store bought) then you may add 1-2 tablespoons of sugar/maple syrup to this recipe.

The Herbs. I use fresh basil and oregano in this sauce recipe. You could potentially use dried, but I’m not sure if the exact measurements, so you’ll have to add, taste, and adjust. Remember! You can always add more, so don’t overdo it 😉

Simmer. I let my sauce simmer over low heat for 2 hours. You could enjoy this sauce right away, but I like to let all the flavors come together for the most flavorful tomato sauce. You could also let it simmer for longer too.

Sauce Consistency. Because we’re using whole roasted tomatoes in this sauce, there will be tomato seeds in it. That doesn’t really bother me, but if you like a smoother sauce feel free to try to blend it with a high speed blender. You could could also try to scoop some of the seeds out of the roasted tomatoes before adding them to the pot with the rest of the ingredients. Straining the sauce won’t really work because then you’ll be left with a super thin, watery sauce.

Storing Your Tomato Sauce

This recipe makes 12 cups (96 ounces) of sauce. If you’re not planning to enjoy it all within a week you can freeze it for later!

For long term storage, you can fill gallon sized storage bags with the cooled sauce, squeeze any excess air out, seal and lay the bags flat on a baking sheet. Place the whole sheet pan in the freezer, then once frozen you can remove the baking sheet and store the sauce more easily in your freezer. When you’re ready to use it, you can thaw it in the fridge and then heat it up in a saucepan.

Ways To Enjoy This Sauce

Pasta. This is the obvious way to enjoy this Caramelized Onion and Garlic Roasted Tomato Sauce.

Toss in your favorite gluten-free noodles, and maybe top with a few plant-based meatballs.

Pizza. The best way to use up leftover sauce… family pizza night! This sauce was SO GOOD on pizza👌🏻. I used Banza chickpea pizza crusts, a generous layer of this Caramelized Onion and Garlic Roasted Tomato Sauce spread over the crust, topped with vegan mozzarella cheese, my homemade vegan parmesan cheese, Abbot’s Butcher plant-based ground “beef”, and shiitake mushrooms. The best pizza! 🍕

More ideas. Lasagna, Eggplant Parmesan, Gnocchi, Spaghetti Squash, “Meatball” Sub, Garlic Bread Dipping Sauce…. And more! You get the idea.

I’m pretty proud of this tomato sauce recipe, it turned out better than I anticipated. I hope you love it too! It’s simple, flavorful, and a must have recipe in your recipe index for pasta night! Let me know what you think down below below in the comments section, as well as giving it a five rating ⭐️⭐️⭐️⭐️⭐️ so that others can discover this vegan, homemade Caramelized Onion and Garlic Roasted Tomato Sauce recipe! Tag me on Instagram, Facebook, or Pinterest if you make it!