Empty the jello package into a large bowl. Carefully pour the boiling water over the top, then stir until the jello is dissolved.
Add the frozen strawberries and stir until mostly thawed. Pour this mixture into a large blender.
In a small bowl, roughly mash together the banana and lemon juice. Add this to the blender.
Add the 2 cups of sour cream. Blend for about 30 seconds, some lumps are okay.
Prepare a jello mold or a 10-12 cup bundt pan with nonstick spray. (Or just use a pretty bowl, no need to spray).
Pour the jello into the prepared pan, cover tightly, and refrigerate for several hours or overnight, until completely chilled.
To invert the jello, place a plate over the mold and flip. If the jello doesn't come out, fill a large bowl with hot water and hold the bottom of the mold in the water for no more than 1-3 seconds, then invert again. (This will help melt the outer edge, releasing the jello.)
Serve the jello with fresh strawberries.