Toss apple slices and lemon juice in a small bowl. Cut baguette crosswise into 4 sections. Cut each section in half lengthwise. Remove the soft inner portion of bread, leaving a 1/4-inch-thick shell. (Reserve the inner bread for another use.)Advertisement
Top the bottom pieces of bread with lettuce, turkey, Brie and the apple slices. Spread mustard on the top pieces and set one on each sandwich. Serve immediately or wrap and refrigerate for up to 4 hours.
Tip: To cook turkey, place 1 turkey breast tenderloin in a skillet with 1 cup water. Bring to a boil. Reduce heat, cover and simmer until internal temperature reaches 165 degrees F, 20 to 25 minutes. Remove from the pan. When cool enough to handle, shred with 2 forks. Refrigerate any remaining turkey in an airtight container for up to 3 days or freeze for up to 2 months.