@SarahGen-- You only use vinegar?! Isn't the flavor too strong then?! I don't think my stomach could handle that. Dry white wine and vinegar is the best. It's perfect. The only exception I can make to that is mignonette sauce gelatin recipe that is used in some seafood restaurants. I believe they only use vinegar for those.
I make my mignonette with both vinegar and wine and I let the sauce rest in the fridge for a few hours. It really absorbs the flavor of the pepper that way and the shallots become nice and tender. Delicious!