Bloom the powdered gelatin in the water.

Have a very sharp knife ready.

Hull the strawberries.

Peel the kiwi and orange, then cut them into pieces that will fit neatly in the sandwich.

Pour the well-chilled heavy cream into a mixing bowl, add the sugar, then whip until softly whipped (about 80% whipped).

Microwave the bloomed gelatin for about 10 seconds, just until liquefied.

Add the melted gelatin, rum, and sweetened condensed milk to the whipped cream, then whip again until the cream holds firm peaks.

Spread a thin layer of cream over one slice of sandwich bread. Arrange the strawberries in a straight line down the center (3 to 4, depending on their size), then cover generously with cream until the fruit is completely hidden. Spread a little cream on a second slice of bread and close the sandwich.

Wrap the sandwich tightly in plastic wrap, then draw a line on the wrap with a marker in the direction of the strawberry row to use as a cutting guide.

Spread a thin layer of cream over one slice of bread. Arrange the kiwi, orange, and strawberry pieces on top, then cover generously with cream. Spread a little cream on a second slice of bread and close the sandwich.

Wrap tightly in plastic wrap without drawing a line; this sandwich will be cut diagonally.

Refrigerate the sandwiches overnight to firm up the cream and make clean slicing easier.

For the strawberry sandwiches: briefly warm the knife blade with hot water or a flame, then slice through the plastic wrap along the marked line without pressing down, using gentle back-and-forth motions. Wipe or rinse the blade between cuts, trim the ends, remove the wrap and crusts if desired, then cut again into neat cubes.

For the fruit sandwiches: cut diagonally with a clean, very sharp knife. Remove the crusts if desired, depending on the presentation you want, and clean the blade between cuts.