In a medium pot, combine the oil, onions, and garlic. Add a pinch of salt. Turn the heat to high. As soon as the onions and garlic begin simmering, give them a stir, turn the heat to low, and cover the pot. Cook for 10 minutes.
Uncover the pot, add a pinch of crushed red pepper flakes, stir once or twice, raise the heat to high; then add the wine. Let it simmer for 2 to 3 minutes or until the alcohol smell dissipates.
Add the tomatoes. Using scissors, snip the tomatoes into smaller pieces. Season with a generous pinch of salt, and cook at a gentle simmer for 15 minutes.
Transfer the sauce to a blender or food processor. Add the basil. Purée until smooth. Taste and adjust with more salt if necessary. (Alternatively use an immersion blender to purée)
