Dissolve gelatin in boiling water.
Add berries, stirring occasionally till thawed.
Add pineapple and banana.
Pour half the mixture into an 8x8x2-inch pan.
Chill till firm.
Spoon sour cream over chilled gelatin, spreading in an even layer; pour remaining gelatin over.
Cut in 9 squares; serve on lettuce ruffles.
Garnish with dollops of sour cream and whole strawberries split in half from top almost to bottom.