How to Make It
Preheat the oven to 350°. Spread the walnuts in a pie plate and toast for 8 to 10 minutes, until fragrant. Let cool.
In a blender, puree the cooled walnuts with the water until smooth. Add the vinegar and pulse to combine. Using a fine-mesh sieve set over a small bowl, strain the walnuts, pressing on the solids; discard the solids. Whisk in the olive and walnut oils and season the dressing with salt and pepper.
In a serving bowl, combine the lettuce, escarole and beets. Add the vinaigrette and toss well; serve.