In a bowl, mix shrimp, salt, black pepper, paprika, and 1 garlic clove. Set aside.
Heat oil and butter in a big pan on high. Add shrimp in a single layer. Sear for 1 minute on each side.
Lower heat to low. Add the remaining minced garlic, ginger and chopped onion to the pan. Cook for around 3 minutes, until soft and fragrant.
Pour the coconut milk into the pan. Stir in fish sauce, sugar, and lime juice. Simmer for 2 minutes. Add lemongrass, scallions, and chile flakes, and let cook for another 2 minutes.
Add cilantro and return shrimp to the pan. Stir and simmer for 1 more minute until heated through.
Top with more cilantro, fresh red chile rings, and a pinch of black pepper. Serve immediately.
Leftovers will keep in an airtight container in the refrigerator for 3-4 days.