How to Make It
In a shallow dish, whisk the flour with the cayenne and the 1/2 teaspoon of salt. In a second shallow dish, mix the panko with the shredded coconut. Add the coconut milk to a small bowl.
Season the shrimp with salt. Working with 1 shrimp at a time, dredge it in the flour mixture, then dip it in the coconut milk, letting the excess drip off. Coat the shrimp in the panko mixture. Transfer to a plate. Repeat to coat the remaining shrimp.
In a large cast-iron skillet, heat 1/4 inch of oil until shimmering. In 2 batches, fry the shrimp over moderate heat, turning, until golden and crisp and cooked through, about 3 minutes. Drain briefly on paper towels and serve hot with lemon wedges.