Process peanuts in a food processor until thick, approximately 2 minutes. (You can go longer if you prefer the peanut butter to be even smoother.)
Combine the strawberries, port wine, water, lemon and sugar in a medium skillet. Bring to boil, then reduce and simmer on low heat until berries break down and liquid thickens, about 10 minutes. (If desired, pour the strawberries through a sieve to remove the chunks.)
Spread a small amount of butter on one side of each piece of bread. On the other side, spread the peanut butter on half of the pieces and jelly on the other ones. Add a couple pieces of banana and combine the slices for each sandwich.
Spray a grill pan or skillet with cooking spray and heat on medium high until bread toasts, approximately 3-4 minutes on each side.