Step 1Place the currants in a medium bowl, add boiling water to a level one-half inch above the currants and let them stand for 30 minutes. Drain and reserve the soaking liquid.
Step 2In a large skillet, heat the oil over medium-high heat. Add onions and cook, stirring, until they begin to soften, about 7 minutes. Reduce heat to medium-low and continue cooking, stirring occasionally, until onions are soft and very lightly browned, about 15 to 20 minutes, adding 2 to 3 tablespoons of the currant soaking liquid when onions begin to look dry.
Step 3Add the currants and another 2 to 3 tablespoons of their soaking liquid and cook for 5 more minutes, stirring. Stir in the cinnamon and allspice and cook for 2 more minutes. Remove from heat and let the mixture cool to room temperature. Stir in the pine nuts.
Step 4In a food processor, puree the garbanzo beans in 2 batches with the tahini, lemon juice and 4 to 5 tablespoons of the bean liquid until very smooth. Scrape the mixture into a large bowl.
Step 5Mash the potatoes until smooth with a potato masher or pass through a ricer. Stir the mashed potatoes into the pureed mixture and mix thoroughly. Season with salt.
Step 6Line an 8-inch square baking pan with plastic wrap, leaving 4 to 5 inches of overhang on all sides. Wet your hands with cold water and use them to spread half of the garbanzo mixture evenly on the bottom. Spread the onion mixture evenly on top; it will be a rather thick layer. With wet hands, spread the other half of the garbanzo mixture on top of that. Fold in the overhang to enclose the pate. Weight the pate with a small cast-iron skillet, a plate topped with two 16-ounce cans or something of similar weight, and refrigerate for 2 to 3 hours.
Step 7To serve, bring the pate to room temperature, invert it onto a serving plate and remove the plastic wrap. Sprinkle the top lightly with cinnamon (you can do this decoratively through a doily). Cut into squares.