Begin making the plum sauce by combining the plums, apple, chile, sugar, vinegar, and 2 tablespoons of water in a saucepan. Warm the mixture gently over low heat, stirring occasionally to help the sugar dissolve completely. Once dissolved, increase the heat and bring to a boil.
Reduce the heat slightly, partially cover the pan with a lid, and let the sauce simmer gently for about 30–40 minutes. The fruits should break down into a thick, jam-like consistency with only a small amount of liquid remaining. Remove from the heat and allow the sauce to cool to room temperature.
Pour enough oil into a nonstick frying pan to lightly coat the bottom and heat over medium-high heat until shimmering. Carefully add the tofu pieces to the hot oil and fry for 3–4 minutes, turning them gently with a spatula or tongs, until all sides are crispy and golden brown.
Lift the tofu out of the pan and transfer to a plate lined with paper towels to drain any excess oil. Set aside and keep warm while you prepare the pancakes.
To assemble and serve, lay a pancake flat on your work surface. Spread a thin layer of the cooled plum sauce across the center, then top with pieces of the crispy fried tofu, a scattering of sliced scallions, and some julienned cucumber strips. Roll the pancake up tightly to enclose all the fillings and enjoy immediately while the tofu is still warm and crispy.