Heat the olive oil in a large saucepan over medium heat until it shimmers and releases a fragrant aroma.
Add the minced garlic to the hot oil and sauté for about 30 seconds until fragrant and slightly golden, but not browned.
Stir in the chopped ripe tomatoes and cook, stirring occasionally, until they soften and release juice, about 10 minutes. You should see the mixture bubbling gently and turning a richer red.
Sprinkle in the dried red chili flakes if you like some heat, then add a teaspoon of sugar to balance the acidity of the tomatoes.
Pour in a tiny splash of fish sauce, stirring well—you'll notice an instant umami boost and a slight scent enhancement.
Reduce the heat to low and let the sauce simmer gently for about 15-20 minutes, stirring occasionally until it thickens to a glossy, smooth consistency.
Taste the sauce and adjust seasoning if needed; it should be rich, slightly tangy, with a hint of spice and depth from the umami ingredient.
Remove the sauce from heat and stir in fresh basil leaves for a fragrant, herbal finish.
Serve the sauce hot over cooked pasta, or use as a flavorful base for other dishes, garnished with additional basil if desired.
