The instructions for the basting sauce I tried to make called for heating olive oil, butter, Dijon mustard, vinegar, and pepper and then whisking together until smooth.

I heated the oil, added the butter to melt, and then added the mustard. I skipped the vinegar.

When I added the mustard, it turned into tiny clumps and no amount of whisking would get it incorporated. What did I do wrong?
I don't think it was leaving out the vinegar; could it have been that?

  • Dry mustard? Or prepared?
    – bmargulies
    Commented Jul 31, 2010 at 16:10
  • Sorry...prepared. The recipe just said Dijon mustard so I assumed it meant prepared.
    – apaderno
    Commented Jul 31, 2010 at 16:28
  • Interesting recipe. I'm not familiar with marinades that require heating beforehand.
    – Ocaasi
    Commented Jul 31, 2010 at 17:15
  • Uff! I used the wrong word, Ocaasi. It is a baste for broiled swordfish. Will edit. Thanks for pointing that out.
    – apaderno
    Commented Jul 31, 2010 at 17:17

2 Answers 2


The reason that your basting sauce flopped was the recipe was calling for an emulision (basically, a vinegrette) and by leaving out the vinegar you are changing the one of the basic building blocks of the dish. The sauce will require that you add the fats to the mustard as it will clump as experienced if you don't. The mustard in the original recipe is used as an emuslifer and may need to be cut down without the addition of the vinegar. To build a sauce like this, you should start with the vinegar, add the seasonings and any emulisfers (in this case, the mustard) and slowly drizzle the fats into the resulting mixture until all has been incorperated. You will still get a smooth sauce as long as you keep the order even if you leave off an ingredient or two.

  • Um actually you're kind of wrong on a few points there. For one, mustard dissolves quite nicely in fats, you just need to add the fat to the mustard and not the other way around. The clumping is not a broken sauce in this case, it is simply the mustard not dissolving. When chefs talk about a broken sauce, they mean that the emulsion has split. Curdling--clumping--is a different thing and won't happen in sauces that don't contain dairy or certain proteins. -1, sorry.
    – daniel
    Commented Aug 1, 2010 at 19:05
  • i was having a hard time getting the knowledge through my fingertips when I wrote it the first time. However, I don't think that what happened to the sauce had anything to do with curdling. You have to introduce either acid, bacteria, or heat to produce curdling as it is a factor of denaturing the protien strands in the milk/butter. Anyway, As written the answer was crap, hopefully this one is better. Commented Aug 5, 2010 at 0:16

When mixing, add liquids to solids (or semisolids), not the other way around. Next time, make the recipe the same but have the mustard in another bowl and whisk your butter/oil mixture into the mustard. I'd also not omit the vinegar, as the acidity would cut the richness of the fats.,

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