In a medium bowl, dissolve jello in 1 c boiling water. Mash bananas with a fork until you have a mixture of banana mush, with some small chunks left for texture. Add to jello. Add strawberries and their juice, along with drained pineapple. Stir in walnuts. Put about half the fruited jello mix in a bowl or mold. Refrigerate until partially set. Spread on sour cream in a smooth layer. Pour remaining jello on top and chill until set. Unmold and serve. Note: I sometimes fold the sour cream through the entire fruit-jello mixture, at the thickened rather than partially set stage, for a different texture change of pace. Posted to EAT-L Digest by Kim Malo on Nov 22, 1997