- 2/3 cup white verjus (juice of unripe fruits, primarily grapes) or 3 tablespoons fresh lemon juice
- 1/2 cup Tawny Port
- 3 tablespoons sugar
- 1 1/2 tablespoons Sherry vinegar
- 1/2 teaspoon salt
- 1/4 teaspoon black pepper
- 3 tablespoons pure walnut oil
- 1 lb frisée (pale leafy parts only), torn into small sprigs (6 cups)
- 1 lb Belgian endives (3 or 4), trimmed and cut crosswise into 1/4-inch-thick slices (3 cups)
- 1/2 lb radicchio, halved lengthwise, cores and coarse center ribs discarded and leaves torn into bite-size pieces (3 cups)
- 12 (1/2-inch-thick) slices pain de mie, Pullman loaf, or firm white sandwich bread, crusts discarded
- 1 lb chilled foie gras terrine, unmolded if necessary
- Fleur de sel or kosher salt to taste
- Bring verjus, Port, and sugar to a boil in a 1-quart heavy saucepan, stirring until sugar is dissolved, then boil until syrupy and reduced to about 1/3 cup, 8 to 12 minutes.
- Whisk together vinegar, salt, and pepper in a bowl, then add walnut oil in a slow stream, whisking.
- Just before serving, toss frisée, endives, and radicchio in a bowl with just enough vinaigrette to coat.
- Put oven rack in upper third of oven and preheat oven to 400°F.
- Toast bread slices on a baking sheet, turning over once, until pale golden, about 8 minutes. Cut foie gras terrine into 12 slices (about 1/4 inch thick) and put 1 on each toast (trim toasts to size of foie gras if desired). Sprinkle lightly with fleur de sel, then halve toasts diagonally. Let toasts stand, loosely covered with plastic wrap, 5 to 10 minutes, to bring foie gras to room temperature.
- Put 1 foie gras toast on each of 12 plates and drizzle with Port glaze, then divide salad among plates.