Heat the olive oil in a skillet over medium heat

cook the onion and garlic in the hot oil until tender, about 5 minutes.

Stir the tomatoes, red pepper flakes, vinegar, and sugar into the onion and garlic mixture

bring to a boil

reduce heat to low, and simmer until the flavors blend to your liking, 45 to 60 minutes.

Stir the basil into the sauce

season with salt and pepper.