Rinse and soak dried shrimp for 10 minutes. Drain well and give the softened dried shrimp a rough chop.
Heat up 2 tablespoons vegetable oil in a medium saucepan. Add prepared dried shrimp and fry until golden brown, about 4 to 5 minutes. Remove with a slotted spoon and set aside.
Combine shredded radish and 1 cup (240ml) water in a medium non-stick pot. Cover and bring to a boil. Add salt, ground pepper, and sugar.
Cover and cook over low heat for 10 to 15 minutes, stirring occasionally, until radish becomes soft and most of the liquid has evaporated.
Add prepared dried shrimp, crispy fried shallot, rice flour and remaining 3 cups (720ml) water into the pot.
Stir with a spatula and cook until mixture becomes a thick paste, about 2 to 3 minutes.
Pour thicken radish paste into prepared 8” x 8” deep square pan. Smoothen the surface with a plastic wrap.
Prepare a steamer with rack.
Transfer pan into steamer rack and steam for 45 minutes.
When done, remove from steamer rack and allow it to cool completely.
Flip the pan over onto a cutting board. Cut into 16 slices.
To serve, coat a non-stick fry pan with 2 tablespoons vegetable oil. Pan fry slices of steamed radish cake for 5 minutes. Flip the pieces of radish cakes and pan fry for another 5 minutes until golden brown. Pan fry in two batches.
Transfer onto a serving dish and garnish with green onions and crispy fried shallots, if using.
Serve immediately with sweet chili sauce and hoisin sauce.