Step 1 In a small, heavy saucepan, combine the honey, molasses and butter over low heat. Cook, stirring a few times, until the butter is melted and the ingredients are well blended; set aside to cool until the mixture is lukewarm.
Step 2 Meanwhile, in a large bowl, thoroughly whisk together the wheat and teff flours, almond meal, pepper, cloves, cardamom, cinnamon, baking powder and salt. Whisk in 1/4 cup of the orange peel and make a well in the center.
Step 3Whisk the eggs into the lukewarm molasses mixture, then add the wet ingredients to the center of the dry ingredients. Using a dough whisk, a wooden spoon or an electric mixer on low, and starting from the center, gradually incorporate the flour mixture until no streaks of flour remain. The dough will be very thick and sticky; if using a mixer, finish by hand if needed. Cover the bowl with plastic wrap and refrigerate for 8 hours or overnight (and up to 2 days).
Step 4Place a rack in the center of the oven and heat to 350 degrees. Line 2 large rimless baking sheets with parchment paper. Have a small bowl with 1 tablespoon vegetable oil at the ready, and apply a thin film of oil to your work surface.
Step 5Divide the heavy dough into 8 equal portions using a butter knife (cut in half like a cake and then each half into quarters). Lightly oil your palms. Working with one portion at a time, gently roll each one — first between your palms and then briefly on the work surface — into a smooth log about 1 inch in diameter. Cut each log into 6 pieces and roll each into a walnut-sized ball. Transfer to the baking sheet, leaving cookies spaced at least 1 inch apart. Repeat three more times with the first half of the dough, oiling your hands as needed.
Step 6Bake until the cookies have nicely risen, show cracks on top and are just firm to the touch but still yield, about 12 minutes. Carefully slide the cookies, together with the parchment paper, to a wire rack. Repeat with the second half of the dough.
Step 7Just before the cookies are done, add the confectioners' sugar to a small bowl. Whisk in 1 tablespoon of the rum, adding more as needed and thinning with hot water by the 1/4 teaspoon, until you have a smooth glaze. While the cookies are still warm, coat them with an even layer using a pastry brush. Decorate with a few pieces of the peel while the glaze is still moist. Allow to cool completely before storing.