I've found that the only way to get it perfectly smooth is by using a high-powered blender. I use a Vitamix these days, and the sauce gets super smooth! Otherwise, just be patient and give the sauce plenty of time to blend (5 minutes or so). I've made this recipe using Cuisinart food processor, and while the sauce could have u003cemu003elooked u003c/emu003esmoother, I didn't notice a difference in mouthfeel.