Preheat oven to 400 degrees. Butter a 9-by-5-inch loaf pan, and line the bottom and sides with buttered parchment paper.
In a large bowl, stir to combine hot water and honey. Add salt, sugar, baking soda, and baking powder; stir to dissolve. Add rum, fennel seeds, nutmeg, cinnamon, and crystallized ginger; stir to combine. Gradually add rye flour, and mix well; gradually add all-purpose flour, and continue stirring. Add orange zest, raisins, and almonds, stirring for about 25 strokes to fully combine.
Transfer batter to prepared pan, and bake for 10 minutes. Reduce oven temperature to 350 degrees and continue to bake until deep brown and a skewer inserted in the center of the cake comes out clean, about 80 minutes.
Transfer pan to a wire rack to cool. Remove cake from pan, turn it on its side, and remove the parchment paper. When cake is completely cool, wrap in aluminum foil and allow to sit at room temperature for 1 to 2 days to allow the flavor to develop.
Cut cake into 1/2-inch slices, and cut each slice in half. To serve, spread with unsalted butter, top with warm applesauce, and drizzle with honey.