All-Purpose Flour (Best Option)
1 tablespoon per 1 tablespoon of cake flourAll-purpose flour has a moderate protein content that allows it to thicken tomato sauce effectively without imparting off-flavors. It absorbs liquid well and helps achieve a balanced viscosity.
For best results, whisk the flour into a small amount of cold water or olive oil before adding to the sauce to prevent lumps. Cook the sauce long enough to eliminate any raw flour taste.
Compared to cake flour, the sauce may be marginally thicker and less delicate, but the difference is minimal and generally imperceptible in tomato sauce applications.