Special equipment: a fine sieve a deep fryer, slotted spoon or spider and rasp
Roughly chop the raw shrimp and place in a large bowl.
In a small bowl, whip the egg whites with a fork until frothy. Stir in the cream, salt, pepper, and cumin seeds. Combine with chopped shrimp. Mix well with the jicama, green onion, cilantro, ginger, and kaffir lime leaves.
Press any excess moisture out of the crab meat in a colander. Combine the crab with the shrimp mixture.
Pour the panko into a wide, shallow dish. Scoop out a heaping tablespoon of the shrimp and crab mixture and drop it into the panko. Using your hands, shape the shrimp and crab mixture into round cakes and evenly coat with the panko. Repeat with the remaining mixture and place the crab cakes on a parchment-lined baking sheet. Refrigerate for 30 minutes until firm.
Heat a deep fryer to 350 degrees F or heat 3/4-inch of vegetable oil in a skillet over medium heat, just until the surface of the oil begins to gently ripple. Fry the crab cakes, a few at a time, until crispy and golden, about 2 minutes per side. Remove from the hot oil with a slotted spoon or spider and place on absorbent paper to absorb any excess oil.
Serve with Ginger-Lime Dipping Sauce on the side.
Put sugar, water, ginger, and salt in a heavy-bottomed saucepan. Bring to a boil, then lower heat and reduce to a syrupy consistency (about 15 minutes). Strain through a fine sieve, discard ginger, reserve liquid, and let cool.
In a small food processor, pulse cilantro, lime juice, chile, and green onion (about 30 seconds). Add ginger syrup and pulse until combined.
Serve at room temperature.
*It's important that the shrimp are well chopped or the cakes won't hold together. **Panko, coarse Japanese bread crumbs, can be found in Asian markets or produce shops ***Can be found in Asian markets or produce shops