Heat oil in a small saucepan and add the sliced garlic. Saute till the garlic is golden brown, and then add the diced tomatoes.
Sauté for 2 minutes, and then add salt, black pepper, red chili flakes, and Italian herbs.
Sauté for a minute, and then add ¼ cup of water. Turn heat to low, and let the mixture cook for about 15 minutes. Use a wooden spoon to stir and mash the tomatoes every few minutes.
After 15 minutes, add the tomato paste, along with sugar and vinegar. Cook for about 8 – 10 minutes, and then take off the heat. Use an immersion blender / hand blender for about 30 seconds to make the tomato sauce smooth. Alternatively, let the tomato mixture cool, and place it in a blender. Pulse 2 – 3 times till smooth. Set the tomato sauce aside.