Add the olive oil to a saucepan on medium heat. Sauté the garlic for 1 minute, until it smells great and becomes translucent. Add the chili flakes and cook for 30 seconds. Add the can of tomatoes, mix, and cook until warmed through. Add a little lemon zest, then salt and pepper to taste. Since canned tomatoes are often already salted, you may not need to add any.
If you want a thicker sauce that will stick to pasta better, cook for 10 to 20 minutes to evaporate more of the liquid. Use immediately or keep in a jar in the fridge for later use.