Tear the lettuce into bite-sized pieces. Make a vinaigrette out of the sherry vinegar, walnut oil, lemon juice and vegetable broth, and season with salt, pepper, and sugar.
Chop the walnuts coarsely and the shallots finely. Cut the tofu into small cubes and fry in hot oil on all sides until crisp. Add shallot and sauté briefly. Then add the chopped walnuts, stir frequently until golden brown, and set aside, keeping warm.
Pour the vinaigrette over the lettuce and arrange on the plates. Sprinkle the warm tofu and walnut mixture over the top. Garnish the plates with the cream of balsamic.
Note: This serves four as a side salad. If you want to serve it as a main dish, make at least double the amount.