Begin by slicing the beef shank into 4-5 inch pieces. In a pot of boiling water, add the beef along with sliced ginger. Blanch for 30 seconds, then drain and rinse under cold water.

Return the blanched beef to a clean pot and add water until submerged. Add rock sugar, spices, garlic, Shaoxing wine, light soy sauce, and dark soy sauce. Bring to boil, then simmer for 1 hour until fork-tender.

Remove from heat and allow beef to cool at room temperature for about 30 minutes. Transfer to the refrigerator for at least 2 hours or overnight.

Cook scallion pancakes according to package instructions until crispy and golden brown. Keep warm in a low oven.

Thinly slice the chilled beef and prepare the cucumber and scallions. On each pancake, spread hoisin sauce, add scallions, beef, and cucumber. Layer vibrantly.

Roll each pancake tightly, slice in half diagonally for presentation. Garnish with chopped scallions and cilantro if desired. Serve warm.