Heat a large pot over medium heat. Add oil and then add onion and carrot. Saute for 8-10 minutes or until softened. Add in garlic and cook for 1-2 minutes longer. Remove from heat if not adding tomatoes right away to make sure garlic doesn't burn.
Puree tomatoes with a stick blender. Add to the onion carrot mixture. Stir in tomato paste, basil, oregano, red pepper flakes, salt, pepper, and sugar.
Reduce heat to a medium-low and let simmer for at least 20-30 minutes. If time permits, let simmer on low for 1-2 hours, stirring occasionally.
You can use stick blender some more if desired.