Slow-Simmered Tomato Sauce

• 1/4 cup olive oil
• 1 large white or yellow onion, finely diced
• 6-8 garlic cloves, peeled and lightly crushed with the back of a knife
• 1/4 teaspoon crushed red chili flakes, or to taste
• 2 (28 oz) cans whole peeled tomatoes
• 1 teaspoon balsamic vinegar
• 1 bay leaf
• 1 3-inch cinnamon stick
• 1 teaspoon finely grated orange zest
• Salt and freshly ground black pepper to taste

1. In a large heavy-bottomed pot, heat olive oil over medium heat. Add onion and a pinch of salt and cook, stirring occasionally, for 20-25 minutes, or until the onions are golden and sweet. Add garlic and chili flake, and cook, stirring frequently, for another 8-10 minutes, or until the garlic is soft and the onions are amber-colored. Use a potato masher or a wooden spoon to break the garlic up into chunks.
2. Add tomatoes, then rinse out each can with about 1/2 cup water (1 cup total) and add the water to the pot. Use a potato masher or wooden spoon to break up the tomatoes into smaller chunks (you can make this as chunky or smooth as you want, keeping in mind that the tomatoes will break down a bit more as the sauce simmers). Stir in vinegar, bay leaf, cinnamon stick, orange zest, salt, and pepper.
3. Bring the sauce to a boil, then reduce the heat to low. Simmer, uncovered, for about 2 hours, or until the sauce has thickened and coalesced. Discard bay leaf and cinnamon stick, then taste and adjust the seasoning. Serve however you like.
4. The sauce gets even better the next day. It'll keep in a covered container in the fridge for about 4 days, or in the freezer for 4-6 months.

olive oil, white, garlic, red chili, tomatoes, balsamic vinegar, bay leaf, cinnamon, orange zest, salt

Taken from food52.com/recipes/24806-slow-simmered-tomato-sauce (may not work)