Combine the cumin and salt then toss the ribs in the mix to coat well. Cover and refrigerate for 2 hours or longer.
Place the ribs in a steamer pan over boiling water and steam for 1½ hours until soft. Remove from the heat and let cool completely.
To make the dressing, mix together the sugar, sesame oil, vinegar, soy sauce and shaoxin cooking wine. Mix in the garlic, chilli and spring onion. Set aside until needed.
When the lamb has cooled, beat the egg white until you have stiff peaks. Mix the rice flour with about ¾-1 cup water until you have a consistency of double cream. Gently fold in the egg white.
Heat the oil over a moderate heat until hot (around 350ºf/170ºc) - carefully dip a few lamb ribs into the rice flour mix to lightly coat - tap off any excess. Carefully drop into the oil to fry for about 2-3 minutes each side to crispen slightly. Drain on paper towels and keep warm in a warm oven. Repeat with all the other ribs.
Arrange the ribs on a large serving platter. Scatter over the cucumber, then pour over the dressing. Finally, scatter with cilantro and hot with rice.