In a large pot over medium heat, add garlic, onion, thyme and olive oil. Stir and cook for 4-5 minutes, until onions are translucent but not caramelized.
Add tomatoes and basil sprig, stir and bring to a boil. Turn the heat down to a bubbling simmer, cover and cook for 35 minutes while stirring occasionally.
Turn the heat off and transfer the sauce to a blender. You can also use an immersion blender and blend directly in the sauce pot. Add capers and blend until you achieve your desired consistency. I like to leave it a bit chunky – but a smooth sauce is also delicious!
Season with salt and pepper and serve.
Serve with spaghetti, use as a base for pizza, the options are endless!
Store unused tomato sauce in an airtight container in the fridge for up to a week. Or freeze for up to 6 months.