Preparation Boil apple cider in a small saucepan or skillet over moderate heat until reduced to about 2 tablespoons, 5 to 8 minutes. Cool to room temperature. Shave fennel into 1/8-inch-thick slices with slicer. Whisk together reduced cider syrup, vinegar, shallot, salt, and pepper in a small bowl, then add oil, whisking to combine. Toss with fennel, escarole, and lettuce in a large bowl just before serving. Cooks' notes:•Fennel can be shaved and greens can be washed and dried 1 day ahead and chilled separately, wrapped well in dampened paper towels, in sealed plastic bags. •Dressing can be made 2 days ahead and chilled, covered.
Preparation Boil apple cider in a small saucepan or skillet over moderate heat until reduced to about 2 tablespoons, 5 to 8 minutes. Cool to room temperature. Shave fennel into 1/8-inch-thick slices with slicer. Whisk together reduced cider syrup, vinegar, shallot, salt, and pepper in a small bowl, then add oil, whisking to combine. Toss with fennel, escarole, and lettuce in a large bowl just before serving. Cooks' notes:•Fennel can be shaved and greens can be washed and dried 1 day ahead and chilled separately, wrapped well in dampened paper towels, in sealed plastic bags. •Dressing can be made 2 days ahead and chilled, covered.