Preheat oven to 400°F. Spray 6-cup soufflé dish with vegetable oil spray. Coarsely puree half of berries, 3 tablespoons sugar and cornstarch in processor. Transfer to small saucepan. Stir over medium heat until mixture boils and thickens, about 3 minutes. Whisk in peel. Cool completely.
Slice remaining berries. Transfer to medium bowl. Add 1 tablespoon sugar; toss to blend. Beat egg whites in large bowl until soft peaks form. Gradually add 3 tablespoons sugar; beat until stiff but not dry. Fold puree into whites in 3 additions. Transfer to prepared dish. Bake until soufflé is puffed and golden, about 18 minutes. Serve immediately with sliced berries.
