This is my kind of perfect marinara sauce: it's rich, umami, savory and sweet. Gone are the days of subpar jarred marinara, or versions that lean too acidic, or bland. We want aaalll the flavor in all the right places, and this sauce has it, as well as what has now become my irreplaceable secret ingredient. It's so easy, and so so good.
Heat the oil in a deep medium or large pot over medium heat. Once the oil is hot, add the onions and stir to coat them in the oil. Sprinkle with salt and pepper, then add the Italian seasoning, dried basil, and celery seed. Stir and spread the onions out as evenly as possible. Stir periodically until the onions are translucent and starting to caramelize (pick up some color). Add the garlic, stir, and cook until fragrant, about 30 seconds. Add the tomato paste and mix until everything is thoroughly coated and pasty. If the onions look dry or thinly coated, add a little more paste. Cook for another minute or so.
Add the crushed tomatoes and mix everything together, scraping the bottom of the pot so any fond (browned bits) gets worked into the sauce. Add the Worcestershire sauce, coconut aminos, sugar, and salt and pepper to taste. These add flavor and dimension, and the sugar balances the acidity of the tomatoes. Taste and adjust the salt, sugar, or anything else it needs. For the heartier version, stir in the cooked ground beef once all of the sauce ingredients are incorporated.
Turn the heat to medium high to bring the sauce to a simmer, then lower it to medium-low to maintain. If you have time, go lower for a slow bubble. If you need the sauce sooner, keep the heat closer to medium for a more rapid simmer, which evaporates the water faster. Simmer for at least 30 minutes, or up to 2+ hours. The longer it simmers, the more concentrated the flavor gets, as the tomatoes release their water and all the components settle in, get to know each other, and infuse the sauce with their goodness.