Place quartered tomatoes in a food processor and pulse a few times until almost smooth, but a few pieces/chunks remain. If you want a smoother sauce, just pulse a few extra time.
In a large skillet, heat the olive oil over medium heat.
Add the shallot and garlic and saute for 2 minutes to soften, careful not to burn the garlic.
Add the tomatoes from the food processor to the skillet and stir.
Add the sugar, salt & pepper, red pepper flakes and basil and stir again.
Reduce the heat to medium-low and let the sauce simmer for 15-20 minutes until reduced and thickened.
Remove from the heat and pour into a glass jar to reserve if not using immediately.