Put the flour into a bowl and make a well in the center. Pour 1 cup of the beer into the well and whisk until the mixture is just combined. Strain the batter through a sieve into a clean bowl and let it rest, covered, for 1 hour. Before using batter, whisk in additional beer, if necessary, to achieve desired consistency.
In a small bowl whisk together the lime juice, fish sauce and honey until dissolved. Add the water, garlic, scallion and chili slices. Set aside.
Place cleaned crabs in a shallow dish and add enough milk to cover. Soak crabs for 10 to 15 minutes.
In a heavy deep pan heat 2-inches of peanut oil to 350 degrees F. Season the crabs with salt and pepper. Dust the crabs with flour, shaking off any excess. Coat and fry crabs two at a time. Dip each crab into the beer batter and allow extra batter to drip back into bowl. Carefully lower the crabs into the heated oil and fry until golden brown, turning once, about 2 minutes per side. Transfer fried crabs to paper towels to drain. Repeat process with remaining two crabs. Arrange crabs on individual serving plates. Garnish with scallion brushes, cilantro sprigs and lime wedges. Serve immediately with dipping sauce on the side.
Recipe courtesy of Gourmet Magazine