Prepare the crab: If using live crab, humanely dispatch it and cut into serving-sized pieces. Reserve any juices released. If using pre-cut crab, ensure it's fresh and rinsed.

Make the chili paste base: In a food processor, combine the blended dried chilies, minced garlic, grated ginger, and shrimp paste. Process until a rough paste forms.

Sauté aromatics: Heat vegetable oil in a large wok or heavy-bottomed pot over medium-high heat. Add the chili paste mixture and sauté for 2-3 minutes until fragrant.

Build the sauce: Stir in the tomato passata, ketchup, and sweet chili sauce. Cook for another 2 minutes, stirring constantly.

Simmer the sauce: Pour in the water and bring the mixture to a simmer. Add any reserved crab juices. Season with salt and a pinch of sugar if desired.

Cook the crab: Add the crab pieces to the simmering sauce. If using whole crab, add the larger pieces (like claws and body) first. Cover and cook for 5 minutes.

Add remaining crab and finish cooking: Add any smaller crab pieces. Stir gently to coat. Cover and cook for another 5-7 minutes, or until the crab is fully cooked and the shells have turned bright red.

Temper the sauce: Remove the crab pieces from the wok and set aside in a serving dish. While stirring the sauce continuously in a circular motion, slowly drizzle in the beaten egg. This creates delicate ribbons.

Add final touches: Stir in the rice vinegar. Gently return the crab pieces to the wok and toss to coat them evenly in the thickened sauce.

Garnish and serve: Transfer the crab and sauce to a large serving platter. Garnish generously with chopped scallions and cilantro. Serve immediately.