New to the forum, with many other questions on the way, but this has gotten me several times...
I have made roasted shallot vinaigrette both at home with a standard blender and a work with a vitamix (vitaprep?) and for some reason within the first hour the oil separates and the shallots are not fully blending into the mixture, instead becoming very grainy and having a nasty look to them.
I typically use about 10 peeled and broken up shallots tossed in a small amount of olive oil with salt and either black or white pepper. After the roasting I add about 1/4 cup vinegar (have tried several) with just enough oil to lighten the color of the mixture and actually thin it out, since the shallot and vinegar combo is quite thick on it's own.
Several recipes call for much fewer shallots and the addition of other ingredients (garlic, herbs, etc) but I like the subtlety of the shallot on it's own, and so have tried to substitute these ingredients with additional shallots.
What is causing the graininess and separation? Do I need a sharper blade, a faster motor, less shallot overall, less/more acid, less/more oil (usually the color lightens after 5:2 oil to shallot blend) or do I need to add a stablilizer to the mixture such as egg yolk or lecithin?
I have the same trouble with using a blend of highly acidic juices such as lemon or lime as the primary acid in the vinaigrette, although these tend to hold for a couple days rather than a mere hour. Any advice would greatly help.