Using a mortar and pestle, grind dried chili powder, garlic, shallots and ginger until smashed and well combined.
In a bowl, add 100g cornstarch and lightly coat crabs until evenly coated.
In a pot, heat up enough oil for deep frying.
Gently place coated crabs into the hot oil and let it deep fry for 5 –8 minutes, until cooked.
Remove from oil and drain on paper towel lined plate.
In a pan on medium heat, heat up 3 tbsp oil and stir fry spice paste for 5 minutes or until fragrant.
Add chili sauce, sugar, white vinegar, tomato sauce, salt and grated pineapple.
Let it simmer on medium low heat for 15 minutes.
Bring sauce to a boil.
Drizzle in beaten eggs, taking care not to stir until egg ribbon forms.
Once egg ribbon form, add cornstarch slurry into the sauce and mix well until sauce thickens.
Stir in fried crabs
Gently stir in fried crabs and toss well.
Let it simmer, uncovered, for 5 minutes
Transfer chili crab into serving dish. Garnish with a sprig of coriander and serve hot with fried mantous.