To cook this particular tomato sauce, it is important that all of your mise en place is ready, as this sauce is all about timing.
To start, pour the olive oil into a large heavy-bottomed pot and add the garlic. Place the pot over medium-high heat. As the olive oil and garlic heat up, be sure that the tomatoes are ready and close by as they will need to be added as soon as the garlic has turns a light golden brown. The cold/room temperature tomatoes will help to momentarily stop the cooking process, which will prevent the garlic from burning.
As the garlic cooks in the oil, stir and/or gently swirl the pot to keep the garlic moving. It is important to keep a very close eye at this stage — you DO NOT want the garlic to cook unevenly and/or burn as this will produce a very bitter sauce.
As soon as the garlic reaches a nice light golden color, gently add the diced tomatoes. Be careful, as the tomatoes will splatter slightly as they hit the hot oil. Stir the tomatoes, to combine with the garlic. Let cook for approximately 10 to 15 minutes, stirring occasionally to prevent sticking.
Once the tomatoes start to break down, you may need to stir more often.
Let this cook for anywhere from 30 minutes to 1+ hours. The amount of time the sauce will take to cook will vastly differ, depending on how high you have the heat, the water content in your tomatoes etc. Basically, the higher the heat, the quicker it will cook — and the more frequently it will need to be stirred. Also note that as the sauce cooks and thickens, it will also need to be stirred almost constantly. Alternatively, the heat can be turned down, to cook the sauce more slowly.
The sauce is almost done when you stir it and you start to see the bottom of the pot for a second or two. When done, the sauce should have a thick, almost tomato paste-like consistency. This rich thick sauce is what sticks so well to pasta.
Serve this sauce with your favourite pasta or use as the base for other delicious sauces/dishes, such as this
Ragu Bolognese.