Oh, and a towel. I took a little tip from Alton Brown and wrapped a towel around the bottom of the bowl to keep in from sliding around. Either I'm doing it wrong or I'm a lot stronger than AB, because it didn't do a whole lot for me.
The ingredients are very similar to the house vinaigrette, with the only difference being the type of vinegar (champagne versus red wine) and oil (walnut versus canola).
Whisk together the mustard, vinegar and lemon juice in a small bowl. Starting slowly, add the oil while constantly whisking until the entire vinaigrette is nice and creamy. Season with salt and pepper. It's that easy.
I personally liked this a lot more than the house vinaigrette, mostly because it was a little less acidic. I served it as part of a mache salad with beets, goat cheese, and walnuts, and it fit in perfectly. I'll be interested to try it again on a more traditional salad.
To be honest, I couldn't even imagine tasting a difference between walnut and canola oil when mixed with all of those other ingredients. I do think the choice of vinegar matters, as does the overall ratio of ingredients (see below).
A couple of notes:
- This is really just another emulsion, which is one of the reasons you need to start by adding the oil slowly. For a better description, see Michael's Ruhlman post on mayo.
- The house vinaigrette has a 1:2:6 ratio of mustard:acid:oil. This vinaigrette has a 3:8:24 (1:2.7:8) ratio, and the acid is split between lemon juice and a less harsh champagne vinegar instead of red wine vinegar. This is probably what's leading to the less acidic taste here.