1. Melt butter in small, heavy-bottomed saucepan, heating butter slowly until it just starts to bubble.
2. In another small pan, bring lemon juice and white wine vinegar to a boil, lower to a simmer.
3. Meanwhile, put the yolks and a pinch of salt into blender (or food processor), blending yolks well on high speed. With blender still running, gradually add all of the vinegar-lemon juice mixture. Then, with blender still running, add butter very slowly to the mix in a very thin trickle.
4. Once butter is completely incorporated and sauce has thickened, pour Hollandaise in a small bowl and stir in the dill.
5. Let cool for a half hour or so, then cover with plastic wrap (poke a couple of small holes in wrap). Place in fridge and chill until sauce is cold and set.
Keeps for 24 hours or a little longer.
Before using, stir well to blend sauce, especially if it has separated.
Tarragon – add 1 to 1.5 tablespoons snipped tarragon. Dried tarragon may also be used: simply add to wine/lemon mixture for a few minutes to re-hydrate.
Saffron – Steep ¼ teaspoon whole saffron in lemon/vinegar mixture as it is boiling, then add to yolks.
Other tasty herbs to use: basil, mint (fabulous with lamb), rosemary (use a half teaspoon, finely minced- rosemary can be very overpowering in large quantities).
Spices (add to lemon/vinegar while boiling): Freshly ground black pepper, curry, smoked paprika.