Cut a 1/2-inch-thick slice from top of bread, and set top aside. Hollow out bread using a serrated knife, leaving a 1-inch shell; reserve soft bread for another use. Set bread shell aside.
Combine salad mix and next 4 ingredients. Combine dressing and lemon juice; drizzle over lettuce mixture. Toss.
Fill bread shell with lettuce mixture; replace top. Slice and serve.