Step 1Heat oil in large skillet over medium heat. Add garlic and pepper flakes. When garlic gives off its aroma and becomes opaque, add tomatoes. Cook over medium-high heat until tomatoes begin to give off their juice and thicken. Use a wooden spoon or potato masher to stir and help break up tomato pulp. Add basil, either whole or roughly chopped, and salt to taste. Cook until sauce thickens just enough to coat pasta, 10 to 15 minutes.
Step 2When sauce is done, remove it from heat and puree it through a food mill using medium disk. This will remove skins and seeds and create a rough puree without adding air.