Heat oil in a deep fryer to 365 degrees. In a bowl, whisk together the egg and milk. In a separate bowl, stir cayenne, paprika, salt and pepper into the flour. Lightly salt the crab, then dip in the flour, dip in the egg, then in the flour again.
Carefully place crabs into the deep-fryer. Cook for 1 to 2 minutes, or until golden brown on one side. Carefully turn over, and cook until golden on the other side. Drain on paper towels. Garnish with spring onions and set aside.
For the vinegar dip, combine the first four ingredients in a small pan over medium heat and heat gently until sugar is dissolved and chili paste is mixed.
Remove from heat and pour into a bowl.
Stir in the garlic, spring onion, coriander, lime juice and the cucumber and serve immediately.
Recipe by Panlasang Pinoy Recipes™ at https://www.panlasangpinoyrecipes.com/deep-fried-crablets-vinegar-dip-recipe/