1. Thinly slice two shallots; set aside. Finely chop remaining two shallots. Using kitchen shears, cut through shrimp shells along back. Leaving shells on, use a small sharp knife to devein shrimp.

2. Carefully lift one side of shrimp shells; tuck about 1/2 teaspoon chopped shallot onto shrimp. Gently press shells back in place.

3. Combine cornstarch, paprika, salt, and cracked pepper. Add shrimp; toss to coat.

4. In a large nonstick skillet, heat oil over medium-high heat. Add shrimp; cook just until opaque, about 2 minutes on each side. Scatter garlic and reserved sliced shallots over shrimp and cook, shaking pan often, 1 minute. Add sugar, fish sauce, 3 tablespoons water, bell pepper, scallions, serrano pepper, and peppercorns; toss to combine. Cook, shaking pan often, 1 minute. Serve immediately, garnished with cilantro.